Oxide Window Research Articles

Impact of the Ge-Si interfacial barrier on the temperature-dependent performance of PureGaB Ge-on-Si p + n photodiodes

A temperature-dependent study of the near-infrared (NIR) responsivity of Ge-on-Si photodiodes is presented. The diodes, formed as n-Ge islands within oxide windows on n-Si and capped with Ga and B layers (PureGaB), exhibit low dark current of ∼2 × 10−13 A/µm2 and broadband responsivity. Temperature-dependent measurements reveal an inherent potential barrier at the low-doped n-Ge on the n-Si heterointerface. This leads to a decrease in responsivity with decreasing temperatures for wavelengths above 1100 nm. The Al-migration process along the Ge-Si interface, associated with the sidewall passivation and found to be a means of reducing dark current, increases the barrier height. Irrespective of the barrier height, room-temperature responsivity is fully recovered by applying a reverse bias to lower the interface barrier. In the devices with the highest barrier, the responsivity at 1310 nm increased from 4.8 to 164 mA/W, at 0 V and 18 V reverse bias, respectively. An additional increase in maximum responsivity at 1550 nm is attributed to Al-sidewall passivation leading to a measured responsivity of 126.4 mA/W at 18 V reverse bias.

Hydrogen nanobubbles and oxidative windows: Investigating how varying hydrogen concentrations influence seed germination and stress defense

The hydrogen molecule can effectively regulate plant growth and development, improving plant resistance to abiotic stresses. However, studies regarding the optimal concentration of hydrogen and the associated mechanisms of action in organisms are lacking. This study showed that the maximum germination rate of radish seeds decreased from 90 % to 50 % under the stress of cadmium ions (Cd2+), and hydrogen nanobubble (NB) water significantly alleviated the stress effect of Cd2+ on radish seed germination. A hydrogen concentration of 0.8 ppm had the best effect, reducing Cd2+ accumulation in radish seeds by 63.23 % and increasing the maximum germination rate from 50 % to 65 %. At concentrations exceeding 1.2 ppm, the beneficial effect of hydrogen was weakened or even reversed. Consequently, we integrated the concept of the oxidative window into a REDOX balance model and demonstrated that an appropriate hydrogen concentration can effectively maintain the REDOX state within organisms. Transcriptome sequencing analysis revealed that hydrogen NB water modulated Cd2+ absorption and accumulation in seeds by regulating cell wall components, alleviating oxidative stress through oxidoreductase activity, and enhancing nutrient synthesis and metabolism. This collectively alleviated the inhibitory effect of Cd2+ on seed germination. This study is helpful for further understanding the effect of hydrogen concentration on the REDOX balance of seed germination, providing a theoretical basis for selecting hydrogen concentration to improve its effectiveness in agricultural fields.

(Invited) On the Advantage of Deploying ALD-Deposited Gate Oxides for 4H-Silicon Carbide MOS Applications

The wide bandgap semiconductor material 4H-silicon carbide (SiC) has revolutionized the power electronics device market since the commercialization of the first SiC metal-oxide-semiconductor field-effect transistor (MOSFET) in 2012. In the blocking voltage range between 650V-1,700 V, SiC MOSFETs offer a higher maximum switching frequency, lower total space consumption as well as a higher temperature operation range than their silicon (Si) counterparts, e.g., the Si insulated-gate bipolar transistors (IGBT). This has led to the rapid uptake in deployment of SiC MOSFETs in main drivetrain inverter topologies in battery electric vehicles (BEVs).Given the importance the availability of oxides play in the role of any MOS-structure, the successful implementation of SiC MOSFETs into power electronics conversion stages has in no small part been due to its native oxide, silicon dioxide (SiO2). This can easily be thermally grown at temperatures between 1,100°C-1,400°C. This advantage as well as the relatively large conduction band offset of approx. 2.7 eV between SiC and SiO2 make SiO2 the ubiquitous gate oxide in any SiC device.However, interface defect densities are still much more prevalent in SiC/SiO2 systems than in their Si/SiO2 MOS counterparts, and most of these defects originate from the thermal oxidation process, which ends up forming carbon-rich interfaces containing carbon clusters, hydrogen (H) and oxygen (O) vacancies. These defects enhance scattering, increase leakage currents and hence reduce channel mobilities in MOSFETs. This is a major technological issue, leading to specific on-resistances (RON,SP) that are much higher than the theoretical unipolar limit of SiC would allow, hampering the further uptake of SiC MOS technology.In this investigation, we explore the three most used deposition/growth mechanisms that will form an SiO2 layer on SiC and the impact this mechanism will have on the interface quality and high-temperature reliability of MOS-based SiC devices.Lateral MOSFETs (LMOSFETs), metal-oxide-semiconductor capacitors (MOSCAPs) and all other mentioned device structures were fabricated on 10 μm thick, nitrogen-doped (4 x 1015 cm-3) epitaxial layers that were grown on highly nitrogen-doped SiC substrates. LMOSFET devices underwent a conventional implantation schedule for the p-base and n+-source and drain implant, both carried out at 500°C, with the post-implantation anneal carried out at 1,750°C for 45 minutes in Ar (5 slm).Once samples had undergone an initial solvent clean/RCA 1/HF (10%)/ RCA 2/HF (10%) clean procedure, a 1 μm thick field oxide was deposited on the samples through low-pressure chemical vapour deposition (LPCVD). A gate oxide window was opened by means of photolithography, after which the oxide was thinned down to a thickness of approximately 30 nm by means of reactive ion etching (RIE). The final oxide was removed using a wet etch in diluted 10% buffered oxide etch to prevent surface exposure to heavily accelerated and charged particles. The gate oxides were then put down using one of the following oxidation routines: ALD deposition of SiO2 using bis(diethylamino)silane (BDEAS) and an oxygen plasma at 200°C (750 cycles) orALD deposition of SiO2 using bis(diethylamino)silane (BDEAS) and an oxygen plasma at 200°C (750 cycles) plus a PDA in FG ambient (5 slm, 5 % H2) at 1,100°C for 1 h.LPCVD using tetraethyl orthosilicate (TEOS) as a precursor.Direct thermal growth at 1300°C for 5 hrs in diluted N2O (4 slm Ar: 1 slm N2O) ambient. Since samples that had undergone routines 1 and 3 usually show a poor as-deposited oxide quality, a post-deposition anneal was performed on these samples in an oxidation furnace in N2O ambient at 1,300°C for 2 hrs. All N2O treated samples (1,3 and 4) showed an oxide thickness of approximately 60 nm, with the FG-treated sample showing a lower thickness of approx. 35 nm. Conventional metal contact formation was then carried out to finalise the devices.In this investigation, we investigate the current-voltage (I-V), capacitance-voltage (C-V) and constant-voltage time dependent dielectric breakdown (TDDB) performance. We will present evidence that high-quality, highly reliable SiO2 layers, formed by ALD and PDA, can be created. Flatband voltage and hysteresis values will be reduced, compared to thermally grown oxides, and frequency dispersion in accumulation is negligible. The ALD oxide with forming gas PDA has the best performance across the entire dataset at all measured voltages (9.6 MV/cm, 9.3 MV/cm, 9 MV/cm, 8.5 MV/cm, 8 MV/cm). This is due to a different interface chemistry, shown by XPS, HRTEM and SIMS, where Si complexes, such as Si dimers or SixOy groups are broken down into simple Si dangling bonds, which can be readily passivated with a FG anneal. This will be discussed in detail in this talk. Figure 1

Effects of TiO2 thin films on silicon nanowire arrays in heterojunction solar cells

In recent years, the energy crisis has gained increasing attention, with greater emphasis being placed on renewable energy. Currently, solar power is regarded as the most developed form of renewable energy. Many materials have been used in solar cells. Radiofrequency (RF) magnetron sputtering is an effective technique used to produce large-area, easy-to-process thin films. In this study, we fabricated p-layer silicon nanowire (SiNW) arrays by using electroless etching to replace previous multilayer films. TiO2-SiNW array heterojunctions were fabricated by preparing TiO2 as an N layer through magnetron sputtering. Subsequently, the Grey–Taguchi method was used to analyze and optimize p–n heterojunctions with TiO2 films. After the effects of the sputtering parameters (RF power, process pressure, deposition temperature, and deposition time) on surface morphology, material structure, photoelectric conversion efficiency, and reflectivity were investigated, an aluminum-doped zinc oxide (AZO) window layer was added and annealed. Grey correlation analysis revealed a decrease in reflectivity from 8.02225 % to 7.72081 % and an increase in photoelectric conversion efficiency from 0.01915 % to 0.082 %. During the confirmation runs, the TiO2 film was found to be amorphous and wrapped around an array of SiNWs. After the AZO window layer was added, reflectivity increased to 18.04712 %, and the efficiency of photoelectric conversion increased to 0.124 %. In addition, according to the results of the confirmation runs, the AZO film was polymorphic. These experimental results confirm the effectiveness of RF magnetron sputtering, which provides high reflectivity and photoelectric conversion efficiency.

Effect of various layers on improving the photovoltaic efficiency of Al/ZnO/CdS/CdTe/Cu2O/Ni solar cells

The photovoltaic (PV) cell structure containing Al/ZnO/CdS/CdTe/Cu2O/Ni has been simulated using the SCAPS-1D software. The PV device includes a zinc oxide (ZnO) transparent conductive oxide (TCO) window layer, a cadmium sulfide (CdS) buffer layer, and a cadmium telluride (CdTe) absorber layer. Additionally, an electron reflected-hole transport layer (ER-HTL) comprising cuprous oxide (Cu2O) is introduced between the absorber layer and the back metal contact. Aluminum (Al) and nickel (Ni) serve as the upper/top and back contact materials, respectively, interconnecting the layers. The back contact materials, the thickness of the absorber, buffer, and window layers, the acceptor density of the absorber layer, the donor density of the buffer layer, the series and shunt resistance, as well as temperature, were all modified to investigate the PV performance of this structure. The PV performance parameters are evaluated through the open-circuit voltage (VOC), short-circuit current (JSC), fill factor (FF), and power conversion efficiency (PCE). To achieve optimal performance, it is recommended to set the acceptor and donor densities for the absorber and buffer layers at 1017 cm−3. These desired densities can be attained by using a window and buffer layer thickness of 100 nm, an absorber layer thickness of 2500 nm, and an ER-HTL of 50 nm. The optimized model demonstrates PV performance characteristics of 1.4811 V for VOC, 28.682434 mA/cm2 for JSC, 74.91 % for FF, and 31.82 % for PCE under the AM 1.5 G spectrum. Furthermore, it exhibits a quantum efficiency of around 100 % at visible wavelengths.

Highly stable and encapsulation-microstructural cathode derived by self-pressurization behavior in Na-halides-based all-solid-state batteries

The emerging halide solid electrolytes (SEs) possess superior (electro)chemical oxidation stabilities compared to sulfide SEs, but the understanding on their good compatibility toward oxide active materials needs to be further studied. Here, we develop a type of Zr-doped Na3YbCl6 chloride SEs. The optimized composition gains a high ionic conductivity and broad electrochemical oxidation window. The in situ and ex situ analyses verify that the chloride as ionic additive in the cathode is highly compatible with NaCrO2. Importantly, it is revealed that the volume change in the cathode can act a position effect on the microstructure evolution. It promotes to form a special core-shell-like structure with homogeneous chloride encapsulating NaCrO2 grains. Such a soft intimate contact promotes a uniform ion transport and mitigate (electro)chemo-mechanical stresses. The prerequisites generating this specific microstructure are proposed. The main capacity loss of the assembled all-solid-state Na batteries (ASSNBs) only occurs in the initial dozens of cycles, induced by the irreversible O3→O'3 phase transition in NaCrO2. The chloride additives with a soft feature and high oxidation-stability allow a high-quality interface in the oxide cathode and an excellent cycling stability of the ASSNBs.

Herbal and chemical seed potentiations improve theredox health of aged seeds of indigenous aromatic rice cultivars through regulation of oxidative window, gene expression, and restoration of hormonal homeostasis.

The online version contains supplementary material available at 10.1007/s12298-023-01375-9.

Faradaic Rhenium Recovery with Polyvinyl Ferrocene (PVF) Electrodeposited Carbon Electrodes

Rhenium, a valuable rare element used in catalysts and superalloys, is difficult to recover in micromolar concentrations (Schulz, 2017). Electrodes coated with the redox active polymer poly vinyl ferrocene (PVF) have shown the ability to selectively adsorb several transition metal oxyanions, but limited adsorption capacity and longevity remain a challenge for these selective electrosorption technologies(Chen et al., 2021; Kim et al., 2020). In this study, we elucidate the impact of electrochemical deposition conditions on PVF coating as measured by capacitance, rhenium uptake, and longevity. PVF films were electrodeposited onto carbon substrate electrode at three different potentials across the oxidation window of the ferrocene-based metallopolymer to understand how the rate of charge transfer influences the resulting electrodeposited polymer coating. It was observed that PVF films electrodeposited at the peak oxidation current potential of 0.45 V (vs. Ag/AgCl) showed both the highest adsorption of Rhenium (458 ± 61 mg Re/g adsorbent) and capacitance (217 F/g). In comparison, the electrodeposition at 0.35 V and 0.6 V leads to a lower average capacitance 355.36 mg Re/g adsorbent and 342.03 mg Re/g adsorbent respectively. The enhanced performance for 0.45 V electro-deposited electrode can likely be attributed to a more stable deposition structure of the polymer (Pater et al., 1998), which enhances adhesion substrate and charge transfer between the substrate and the PVF. The 0.45 V electro-deposited PVF-carbon paper (PVF-CP) electrode illustrates high capacity and stability, indicating the benefits of polymer coating on selective adsorption of rhenium and prevention of electrode corrosive degradation in capacitive deionization systems. The excellent rhenium uptake and longevity demonstrates potential and will be the platform towards a full techno-economic analysis of the hybrid adsorption system in the future.Method Materials: Polyvinyl ferrocene (34801-99-5, produced by Polysciences, U.S.) and tetrabutylammonium perchlorate (1923-70-2, for electrochemical analysis, ≥99%, produced by Sigmar Aldrich Chemistry, U.S.) were used for electrodeposition. Carbon nanotubes (multiwalled, outer diameter of 7−12 nm, length of 0.5 - 10 μm, >99% carbon) were used as conductivity additives in dip coating electrode fabrication. Toray paper (carbon fiber composite carbon paper, produced by FuelCellStore) was used as the substrate for ferrocene polymer deposition under all conditions. Electrodeposition Electrodeposition performed on 2 cm x 1 cm rectangles of carbon paper substrate attached to copper wire with copper tape in a three-electrode cell configuration with a quasi-Ag/organic solution reference and CP counter electrode. 0.35 V, 0.45 V and 0.6 V were applied respectively to the working electrode in 2 mg/mL PVF solution until 0.12 C of charge had passed. Dip the electrodes into chloroform twice to rinse and stored the electrodes in the Milli-Q water. Cyclic Voltammetry (CV) CV test was performed in a three-electrode cell configuration with PVF deposited carbon paper as working electrode, platinum wire as counter electrode and Ag/AgCl reference. The voltage was swept between 0 V and 0.7 V in 0.5 M sodium perchlorate solution to capture characterize redox peak around 0.35 V. Rhenium Uptake The adsorption and desorption experiments were performed in the same three electrode cell but with a solution containing 1 mM NaReO4 or 10 mM NaCl, respectively. The voltage on working electrode maintained 0.8 V for adsorption and -0.8 V for desorption with stirring bar on the bottom stirring at 300 rpm for an hour.ResultsThe deposition happens when the positive charges transferred to the PVF that diffuse to the CP surface. The positive charged ferrocene groups combine with perchlorate, which decreases the solubility of PVF and leads to the deposition. According to the gravimetric mass measurement, the deposition mass range for 0.6 V, 0.45 V and 0.35 V are 0.1 – 0.25 mg, 0.2 – 0.35 mg and 0.4 – 0.55 mg, respectively. Comparing with theoretical deposition mass (0.26 mg, calculated from the total charge transfer), higher transition current and shorter deposition time promote a more sufficient charge transfer and a more localized deposition on the electrode interface. The CV plot (Figure 1(a)) elucidates the prominent specific capacitance for 0.45 V deposited electrode (216.50 F/g on average) and an obvious oxidize peak positive movement for 0.35 V deposition, which is corresponding to a higher deposited mass (0.4-0.55 mg) that may lead to a higher resistance. The mass normalized Re uptake reaches 457.87 mg Re/g polymer with a regeneration rate of 64.47%. For next step, the longevity test will be performed to obtain a further understanding to the depletion of regeneration rate along the increase of cycle number.

Li-Ion Battery Active Material Impedance Analysis I: Comparison of Measured NCM 111 Kinetics with Butler-Volmer Equation Based Predictions

The expression for the exchange current density to describe the intercalation kinetics of Li-ion battery materials proposed by Newman and coworkers has been used extensively for battery modeling, however its applicability to existing battery materials should be validated. Here we show an electrochemical impedance spectroscopy (EIS) analysis of the kinetic behavior of NCM 111 as a function of electrolyte salt concentration and state-of-charge (SOC) and compare it to the proposed theory. An areal capacity dependent EIS analysis first gives insights into the feasibility of measuring kinetic and transport parameters, including the solid diffusion resistance of lithium, showing that low-areal capacity electrodes are required to predominantly probe the kinetics. We then show how the charge transfer kinetics follow a Butler-Volmer type concentration dependent behavior for lower concentrated electrolytes (≤1.5 M) but deviate from the proposed theory at higher salt concentrations. A further SOC dependent analysis shows how NCM 111 generally follows the proposed theory of U-shaped symmetric kinetics, but the limited oxidative stability window leads to practically asymmetric kinetics for charging and discharging. This asymmetry is visible in NCM 111 lithiation and delithiation rate tests, where upon lithiation the kinetics generally become slower for higher degrees of lithiation, limiting the performance.

Magnesium Polymer Electrolytes Based on the Polycarbonate Poly(2-butyl-2-ethyltrimethylene-carbonate).

Magnesium electrolytes based on a polycarbonate with either magnesium tetrakis(hexafluoroisopropyloxy) borate (Mg(B(HFIP)4)2) or magnesium bis(trifluoromethanesulfonyl)imide (Mg(TFSI)2) for magnesium batteries were prepared and characterized. The side-chain-containing polycarbonate, poly(2-butyl-2-ethyltrimethylene carbonate) (P(BEC)), was synthesized by ring opening polymerization (ROP) of 5-ethyl-5-butylpropane oxirane ether carbonate (BEC) and mixed with Mg(B(HFIP)4)2 or Mg(TFSI)2 to form low- and high-salt-concentration polymer electrolytes (PEs). The PEs were characterized by impedance spectroscopy, differential scanning calorimetry (DSC), rheology, linear sweep voltammetry, cyclic voltammetry, and Raman spectroscopy. A transition from classical salt-in-polymer electrolytes to polymer-in-salt electrolytes was indicated by a significant change in glass transition temperature as well as storage and loss moduli. Ionic conductivity measurements indicated the formation of polymer-in-salt electrolytes for the PEs with 40 mol % Mg(B(HFIP)4)2 (HFIP40). In contrast, the 40 mol % Mg(TFSI)2 PEs showed mainly the classical behavior. HFIP40 was further found to have an oxidative stability window greater than 6 V vs Mg/Mg2+, but showed no reversible stripping-plating behavior in an Mg||SS cell.

Electrochromic Glass Design with Solar Energy

With the effect of the use of non-renewable energy sources, our world is facing the danger ofglobal warming. The use of fossil fuels increases the rate of carbon dioxide emitted into the atmosphere,and thus, global warming, unfortunately, brings climate changes with it. Minimizing this danger can onlybe achieved by turning humanity towards renewable energy sources. Solar energy is a reliable,environmentally friendly and inexpensive source. The aim of this study is to perform the electrochromicglass by using solar energy without any electricity costs and thus to encourage people to more renewableenergy technologies. In this study, it is desired to present a new technology design that is an alternative tothe classical window glasses used in our country by using solar energy. The solar panel converts the sun'senergy into electrical energy by using solar energy, and with this electrical energy, the opaqueelectrochromic glass changes color and becomes transparent. Thus, the glass makes the interior of the roomshow with this color change. This system, which works with a photovoltaic panel, operates theelectrochromic glass with solar energy without the need for extra energy. For example, with this system, italso eliminates the need for curtains or roller blinds used in working and living areas and provide ease ofuse according to the desired conditions. This system can be used not only for this purpose, but alsoanywhere that is required for smart glass design and has solar energy potential. For this study,electrochromic smart glass obtained by placing polymer dispersed liquid crystal (PDLC) smart materialand this material was sandwiched between indium tin oxide window films with the help of Polyvinyl butyral(PVB) layer. This electrochromic glass system is designed by connecting the connection cable and the onoff switch cable to the photovoltaic panel. In this study, electrochromic glass performance was tried to beanalyzed depending on the exposure time of the photovoltaic panel in the sun.

Imbibitional redox and hormonal priming revealed regulation of oxidative window as a key factor for progression of germination of indica rice cultivars.

The online version contains supplementary material available at 10.1007/s12298-023-01303-x.

A Review of Polymer‐based Solid‐State Electrolytes for Lithium‐Metal Batteries: Structure, Kinetic, Interface Stability, and Application

AbstractSolid‐state polymer electrolytes (SPEs) for all‐solid‐state batteries (ASSBs) have received considerable attention owing to excellent processability, good flexibility, high safety levels, and superior thermal stability. However, the practical application of SPEs is currently restricted by their low ionic conductivity, narrow electrochemical oxidation window, and poor long‐term stability of lithium (Li) metal. These challenges are mainly related to the polymer molecular structures, the dynamic of the polymer electrolyte, and the polymer compound stability at the electrode‐electrolyte interface. In this review, we provide recent strategies and discuss strategies of interest for applications to high‐energy‐density ASSB, particularly the molecular design, ion‐transport dynamic mechanisms of solid polymer electrolytes, and organic‐inorganic composite. Based on recent work, perspectives on future research directions are discussed for developing solid polymer electrolytes.

The Multi-band Survey Telescope at Zhongshan Station, Antarctica

ABSTRACTThe Antarctic Plateau is considered to be the best ground-based astronomical site on Earth. Compared with other middle latitude observatories, the telescopes located in Antarctica have unique advantages in seeing a large fraction of clear nights, continuous observing window in the polar night, and so on. China has operated several generations of telescopes in Antarctica, but has not yet achieved multicolour simultaneous observation with tracking. Multi-band Survey Telescope (MST) is the first multicolour simultaneous survey telescope in Antarctica. It adopts a Newtonian telescope structure which is different from other Antarctic telescopes and is matched with a new alignment scheme suitable for the harsh environment of Antarctica. In addition, MST is equipped with a defrosting indium tin oxide (ITO) window and a high-precision equatorial mount. This paper introduces the optical design, mechanical structure, and analysis of the actual operation of MST in Antarctica. Since March 2022, MST has been carrying out the observation normally in Zhongshan Station, and the operation of MST has provided a new experience for the follow-up design and installation of Antarctic telescopes. We plan to further optimize the design and manufacture of MST, and develop it as a standard model of small-aperture Antarctic telescopes for space debris observations and time-domain surveys.

Technological Causes of p-n-Junction Break-down of Silicon p-i-n Photodiodes

During the manufacture of coordinate quadrant p-i-n photodiodes with a high reverse bias voltage Ubias≥200 V, it was observed the presence of a systematic lack of products at the level of the dark current of one (rarely several) photosensitive element. After measuring the volt-ampere characteristics, it was seen that the cause of this is a breakdown of the p-n junction. Effective methods of increasing the breakdown voltage are reducing the specific resistance of the silicon used, increasing the thickness of the substrate and the depth of the p-n junctions, reducing the concentration of alloying impurities, but these methods should be used in cases that allow the degradation of the relevant parameters to be neglected. In particular, it is necessary to provide a level of technology that reduces the probability of a breakdown. A number of technological factors that can be the reasons for reducing the breakdown voltage of the p-n junction have been established and investigated. Strong influence on the breakdown voltage. have crystallographic defects, in particular dislocations falling into the region of the p-n junction. By reducing the concentration of alloying impurities, it is possible to significantly reduce the density of dislocations with a small increase in the levels of dark currents. This helps to eliminate the probability of a breakdown. After operations of sprinkling chrome-gold on the reverse side of such a substrate, the appearance of breakdowns was detected. The cause of which are defects formed as a result of local melting of silicon when gold "droplets" with a temperature higher than the melting temperature of silicon fall on it, as a result of boiling in the evaporator. Іt is possible to reduce the probability of the appearance of these defects by spraying from closed evaporators or by increasing the etchability of spraying on the damper. During photolithography, in particular, when etching windows in the oxide, etching wedges are formed, which direct the output of the p-n junction to the surface at an acute angle. These areas are places with an increased level of electric field intensity, respectively, places of probable localization of the breakdown. This can be avoided by using photoresists that provide minimal etching wedges. Irregularities between the oxide windows can also lead to a decrease in the probo voltage, the probability of this can be reduced by careful control of the development and exposure operations and the use of defect-free templates. Another reason for a breakdown can be a violation of the p-n junction due to welding of the contact terminals. In this case, it is a thermal breakdown. This can be avoided by increasing the size of the contact pads with their expansion on silicon oxide, accordingly, welding on the surface of the oxide reduces the probability of a hole. Another method is a local increase in the depth of the p-n junction, but in this case additional technological operations must be carried out.

Regulating Lithium Plating/Stripping Behavior by a Composite Polymer Electrolyte Endowed with Designated Ion Channels.

The urgent demand for high energy and safety storage devices is pushing the development of lithium metal batteries. However, unstable solid electrolyte interface (SEI) formation and uncontrollable lithium dendrite growth are still huge challenges for the practical use of lithium metal batteries. Herein, a composite polymer electrolyte (CPE) endowed with designated ion channels is fabricated by constructing nanoscale Uio66-NH2 layer, which has uniformly distributed pore structure to regulate reversible Li plating/stripping in lithium metal batteries. The regular channels within the Uio66-NH2 layer work as an ion sieve to restrict larger TFSI- anions inside its channels and extract Li+ across selectively, which result in a high Li-ion transference number ( ) of 0.6. Moreover, CPE provides high ion conductivity (0.245 mS cm-1 at room temperature) and expanded oxidation window (5.1V) and forms a stable SEI layer. As a result, the assembled lithium metal batteries with CPE exhibit outstanding cyclic stability and capacity retention. The Li/CPE/Li symmetric cell continues plating/stripping over 500h without short-circuiting. The Li/CPE/LFP cell delivers a reversible capacity of 149.3 mAh g-1 with a capacity retention of 99% after 100 cycles.

Hydrogen-Assisted Molecular Beam Epitaxy of SiGeSn

Since its first synthesis in 2003 [1], the ternary alloy semiconductor SiGeSn has seen an increasing interest due to its unique properties in the field of Group-IV semiconductors [2–6]. SiGeSn not only allows the decoupling of its bandgap and lattice-constant by what it is predestined for the epitaxy of strain-reduced heterostructures on the Si platform. Furthermore, SiGeSn becomes a direct bandgap semiconductor at high Sn concentrations. Considering these properties, SiGeSn is an attractive material system for optoelectronic applications. An exemplary heterojunction optoelectronic device is the single confinement heterostructure laser diode, the still missing key component for the monolithic integration of the optical on-chip communication on Si.However, one of the greatest challenges faced by many Group-IV researchers is the epitaxy of SiGeSn bulk alloys with high crystal quality. The temperature induced segregation of Sn results in interstitial Sn atoms and subsequently in acceptor-like defect states, as it was already reported for GeSn [7].In this work, we show the molecular beam epitaxy (MBE) of SiGeSn structures under Hydrogen ambient. First of all, we determined the concentration of the acceptor-like defect states of undoped SiGeSn NA,defect on the basis of capacitance-voltage (C-V) measurements of SiGeSn pin diodes. Furthermore, we investigated Hydrogen-assisted epitaxy as an approach for the reduction of the acceptor-like defect states.All epitaxy experiments were performed in a 6” MBE system, where Si, Ge and Sn are used as matrix materials and B and Sb as dopants respectively. In particular, we investigated the influence of molecular (H2) as well as atomic (H) Hydrogen on the epitaxy process and therefore the quality of the grown structures. For this purpose, the MBE system was upgraded with a Hydrogen atom beam source for the generation of an atomic Hydrogen flux.Since the Sn segregation is affected mostly by the substrate temperature, this critical growth parameter is measured in-situ using an infrared pyrometer, which allows the observation of the dynamic processes on the sample surface [8] and the precise control of the substrate temperature at TSub = 200 °C during the SiGeSn epitaxy.All SiGeSn structures are based on Ge virtual substrates (Ge-VS) on Si(001) [9], followed by a 400 nm thick additional Ge buffer layer. In order to fulfil lattice matching of SiGeSn on Ge, a constant ratio of Si and Sn of Si/Sn = 3.67 was kept for all structures. The Sn concentration was varied in the range of 5 % < cSn < 10 %. For material characterization, 300 nm thick undoped SiGeSn layers were grown on this substrate layer stack (see Fig. 1a). A detailed characterization of the crystallinity and the surface roughness was performed using X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. The comparison of AFM micrographs of SiGeSn layers, grown with and without Hydrogen assistance (see Fig. 1b) show a clear reduction of the surface roughness due to Hydrogen assisted epitaxy.In order to determine NA,defect, C-V measurements on SiGeSn pin diodes (see Fig. 1c) were performed. The diode layer structure, also based on the previously described substrate layer stack, starts with a 400 nm thick p-doped SiGeSn bottom layer with an acceptor concentration of NA = 5x1019 cm-3, followed by an 300 nm thick undoped SiGeSn layer and a closing 200 nm thick n-doped SiGeSn top layer with a donor concentration of ND = 5x1019 cm-3. Subsequently, pin diodes were fabricated using a single mesa process consisting of four basic steps: Mesa structuring using inductive coupled plasma reactive ion etching (ICP-RIE) with HBr, mesa passivation with plasma enhanced chemical vapor deposition (PECVD) grown SiO2, oxide window opening using RIE with CHF3 and metallization using sputtered Al. An exemplary device can be seen in the scanning electron microscopy (SEM) image in Fig. 1d.The SiGeSn pin diodes were electrically characterised by means of C-V measurements using a Keithley 4200 semiconductor characterisation system. For further evaluation, the C-V characteristics of the pin diodes show linear behaviour when plotted on a C-2-V-scaled diagram (Fig. 1e). Under the assumption of a strongly asymmetric pn junction, (ND >> NA,defect), the slope m of the C-2-V characteristics is proportional to NA,defect. In this manner, we determined NA,defect for several SiGeSn pin diodes in dependence of the alloy composition. The results, as shown in Fig. 1f, show an acceptor-like defect concentration between 1017 cm-3 < NA,defect < 1018 cm-3, which is comparable with results reported by other groups for GeSn [7].In our presentation, we will discuss Hydrogen-assisted epitaxy as a promising approach for improving the SiGeSn crystal quality. Figure 1

Top Stack Optimization for Cu2BaSn(S, Se)4 Photovoltaic Cell Leads to Improved Device Power Conversion Efficiency beyond 6%

AbstractEarth‐abundant and air‐stable Cu2BaSnS4−xSex (CBTSSe) and related thin‐film absorbers are regarded as prospective options to meet the increasing demand for low‐cost solar cell deployment. Devices based on vacuum‐deposited CBTSSe absorbers have achieved record power conversion efficiency (PCE) of 5.2% based on a conventional device structure using CdS buffer and i‐ZnO/indium tin oxide (ITO) window layers, with open‐circuit voltage (VOC) posing the major bottleneck for improving solar cell performance. The current study demonstrates a &gt;20% improvement in VOC (from 0.62 to 0.75 V) and corresponding enhancement in PCE (from 5.1% to 6.2% without antireflection coating; to 6.5% with MgF2 antireflection coating) for solution‐deposited CBTSSe solar cells. This performance improvement is realized by introducing an alternative successive ionic layer adsorption and reaction‐deposited Zn1−xCdxS buffer combined with sputtered Zn1−xMgxO/Al‐doped ZnO window/top contact layer, which offers lower electron affinities relative to the conventional CdS/i‐ZnO/ITO stack and better matching with the low electron affinity of CBTSSe. A combined experimental (temperature‐ and light intensity‐dependent VOC measurements) and device simulation (SCAPS‐1D) evaluation points to the importance of addressing relative band offsets for both the buffer and window layers relative to the absorber in mitigating interfacial recombination and optimizing CBTSSe solar cell performance.

Temporal Regulation of Oxidative Window and Hormonal Homeostasis Are the Key Events Regulating Germination Under Salinity and Oxidative Stress

Temporal Regulation of Oxidative Window and Hormonal Homeostasis Are the Key Events Regulating Germination Under Salinity and Oxidative Stress

Study on the Aqueous CdTe Quantum Dots Solar Device Deposited by Blade Coating on Magnesium Zinc Oxide Window Layer.

Aqueous CdTe quantum dots solar cells have been successfully fabricated by the blade coating method on the magnesium zinc oxide (Zn1−xMgxO or ZMO) window layer. Compared with the ZMO mono-window layer, the ZMO/CdS bi-window layer can decrease the interface recombination effectively due to the lower lattice mismatch and fast interdiffusion between CdS and CdTe. Moreover, the high temperature annealing of the CdTe quantum dots absorbed layer passivates the grain boundary of the CdTe crystalline via the replacement reaction of tellurium with sulfur. Finally, the conversion efficiency of our aqueous CdTe quantum dots solar device is improved from 3.21% to 8.06% with the introduction of the CdS interlayer and high temperature CdCl2 annealing. Our aqueous CdTe quantum dots solar devices show a large open circuit voltage and fill factor which are comparable with the conventional devices that are fabricated with organic CdTe quantum dots. We believe that it is the spike-like conduction band alignment between the ZMO and CdTe absorbed layer that reduces the majority carrier concentration, leading to the decrease in interface recombination probability.