Electronic Transport Properties Research Articles

Hydrogenation of silicon-nanocrystals-embedded silicon oxide passivating contacts

We investigate the effect of hydrogen passivation of dangling bonds in silicon oxide passivating contacts with embedded silicon nanocrystals (NAnocrystalline Transport path in Ultra-thin dielectrics for REinforced passivation contact, NATURE contact). We first investigated the differences in electrical properties of the samples after hydrogen gas annealing and hydrogen plasma treatment (HPT). The results show that the NATURE contact was efficiently passivated by hydrogen after HPT owing to the introduction of hydrogen radicals into the structure. Furthermore, we examined the dependence of process parameters such as HPT temperature, duration, and H2 pressure, on the electrical properties and hydrogen depth profiles. As a result, HPT at 500 °C, 15 min, and 0.5 Torr resulted in a large amount of hydrogen inside the NATURE contact and the highest implied open-circuit voltage of 724 mV. Contact resistivity and surface roughness hardly increased when HPT was performed under the optimized condition, which only improved the passivation performance without deteriorating the electron transport properties of the NATURE contact.

Catalytic co-pyrolysis of waste tea residue and waste plastics to carbon nanomaterials: Catalyst support, reaction temperature and product application

The search for cost-effective, high-performance catalysts is crucial in catalytic co-pyrolysis. Different Fe-Mo@X catalysts (X = Al2O3, MgO) and reaction temperatures (600 ℃, 700 ℃, 800 ℃, 900 ℃) were tested to optimize hydrogen production and carbon quality while also exploring CNTs degradation performance. The results indicate that both catalyst type and operating parameters are highly dependent on the growth of carbon nanotubes and hydrogen. The FeMo@Al2O3 catalyst exhibits superior catalytic activity attributed to its more abundant mesoporous structure and higher specific surface area. Specifically, FeMo@Al2O3 achieved the highest yield of carbon nanotubes (84.42%) at 700 ℃, and attained the maximum hydrogen yield (49.57%) at 900 ℃. However, the CNTs synthesized from FeMo@MgO exhibited fewer defects, higher graphitization degree and purity (Raman and TPO). CNTs/MgO significantly enhanced the degradation efficiency of Clothianidin by virtue of their superior electron transport properties and chemical bonding between MgO and CNTs.

Directional Control of the Electronic and Phonon Transport Properties in the Ferroelastic PtSe2

Directional Control of the Electronic and Phonon Transport Properties in the Ferroelastic PtSe₂

Al 0.3 Ga 0.7 N/GaN HEMT Yapısı için QMSA Metodu Uygulanması

In this study, Al 0.3 Ga 0.7 N/GaN high electron mobility transistor (HEMT) structure is grown on a sapphire (Al2O3) substrate by using metal-organic vapor phase epitaxy (MOVPE), and its electron transport and magnetic transport properties are investigated. Resistivity is measured in the 20-350 K temperature range. Hall mobility and Hall carrier concentration are measured in the 0-1.5 T magnetic field range and the same temperature range. Magnetic transport properties are analyzed using quantitative mobility spectrum analysis (QMSA). 2DEG and 3DEG transport mechanisms are separated by using QMSA results.

Strategies for the High Average zT in the Electron-Doped SnTe

We propose a new strategy to achieve a high average zT in electron-doped SnTe by applying the two-band (TB) and single parabolic band (SPB) models to the electronic transport properties of Sn0.97M0.03Te ( M = Ga , In, Bi, and Sb) reported in the literature. To achieve a high average zT at temperatures from 300 to 823 K, both zT at 300 and 823 K should be high with a steadily increasing zT over the temperatures. The p-type SnTe is known to have a light valence band and a heavy valence band that are approximately 0.40 eV apart. The Bi-doped SnTe exhibits one of the highest zT among all the other doped samples at 300 K (0.09) and the highest zT at 823 K (0.9), with a steadily increasing zT in between. The TB model confirms the presence of the resonant state at 300 K which is responsible for the high zT at 300 K. The B-factor, which is related to the theoretical maximum zT, calculated by the SPB model indicates a steady increase in zT with increasing temperature. The temperature-dependent B-factor of the Bi-doped SnTe suggests that the initial position of its Fermi level at 300 K calculated by the TB model may be responsible for the temperature coefficient of the B-factor, which determines the zT at 823 K. According to the SPB model, experimental zT of 0.9 of the Bi-doped SnTe can be further improved to 1.03 (14% improvement) at 823 K upon carrier concentration optimization. To achieve a high average zT in SnTe, electron doping with a dopant that forms a resonant state and placing the Fermi level at the light valence band in the vicinity of the heavy valence band maximum are both essential.

Aromatic systems with two and three pyridine-2,6-dicarbazolyl-3,5-dicarbonitrile fragments as electron-transporting organic semiconductors exhibiting long-lived emissions.

The pyridine-3,5-dicarbonitrile moiety has gained significant attention in the field of materials chemistry, particularly in the development of heavy-metal-free pure organic light-emitting diodes (OLEDs). Extensive research on organic compounds exhibiting thermally activated delayed fluorescence (TADF) has led to numerous patents and research articles. This study focuses on the synthesis and investigation of the semiconducting properties of polyaromatic π-systems containing two and three fragments of pyridine-2,6-dicarbazolyl-3,5-dicarbonitrile. The compounds are synthesized by Sonogashira coupling reactions and characterized by steady-state and time-resolved luminescence spectroscopy. The compounds show efficient intramolecular charge transfer (ICT) from the donor to the acceptor. The photoluminescence (PL) spectra of the solutions of the compounds showed non-structured emission peaks in the visible region, which are attributed to ICT emission. The PL intensities of the solutions of the compounds are enhanced after deoxygenation, which is indicative of TADF. The photoluminescence quantum yields and TADF properties of the compounds are sensitive to the medium. Cyclic voltammetry measurements indicate good hole-blocking and electron-injecting properties due to their high ionization potentials. Photoelectron spectroscopy and time-of-flight measurements reveal good electron-transporting properties for one of the compounds. In general, polyaromatic π-systems with pyridine-3,5-dicarbonitrile fragments demonstrate promising potential for use in organic electronic devices, such as OLEDs.

Synergistic Integration of Amorphous Cobalt Phosphide with a Conductive Channel for Highly Efficient Electrocatalytic Nitrate Reduction to Ammonia.

Electrocatalytic nitrate reduction to ammonia (NO3RR) is regarded as a viable alternative reaction to "Haber Bosch" process. Nevertheless, it remains a major challenge to explore economical and efficient electrocatalysts that deliver high NH3 yield rates and Faraday efficiencies (FE). Here, it demonstrates the fabrication of a 3D core-shell structured Co-carbon nanofibers (CNF)/ZIF-CoP for NO3RR application. Benefitting from the distinct electron transport property of Co-CNF and desirable mass transfer ability from amorphous CoP framework, the as-prepared Co-CNF/ZIF-CoP exhibits large NH3 FE (96.8 ± 3.4% at -0.1V vs reversible hydrogen electrode (RHE)) and high yield rate (38.44 ± 0.65mg cm-2 h-1 at -0.6V vs RHE), which are better than Co-CNF/ZIF-crystal CoP. Density functional theory (DFT) calculations further reveal that amorphous CoP presents a lower energy barrier in the rate determination step of the protonation of *NO to produce *NOH intermediates compared with crystal CoP, resulting in a superior NO3RR performance. Eventually, an aqueous galvanic Zn-NO3 - battery is assembled by using Co-CNF/ZIF-CoP as cathode material to achieve efficient production of NH3 whilst simultaneously supplying electrical power. This work offers a reliable strategy to construct amorphous metal phosphide framework on conducting CNF as efficient electrocatalyst and enriches its promising application for NO3RR.

Effect of vacancy defects on anisotropic electronic transport behaviors of CoN4C2 based 2D devices: a first-principles study

The strong anisotropic electronic transport properties of the single-atom-thick material CoN4C2 monolayer hold immense importance for the advancement of the electronics industry. Using density functional theory combined with non-equilibrium Green’s function systematically studied the electronic structural properties and anisotropic electronic transport properties of the CoN4C2 monolayer. The results show that Co, N, and C single-atom vacancy defects do not change the electronic properties of the CoN4C2 monolayer, which remains metallic. The pristine device and the devices composed of Co, N single-atom vacancy defects exhibit stronger electronic transport along the armchair direction than the zigzag direction, which exhibit strong anisotropy, and a negative differential resistance (NDR) effect can be observed. In contrast to the results mentioned above, the device with C single-atom vacancy defects only exhibits the NDR effect. Among them, the device with the N single-atom vacancy defect regime exhibits the strongest anisotropy, with an I Z/I A of up to 7.95. Moreover, based on the strongest anisotropy exhibited by N single-atom vacancy defects, we further studied the influence of different sites of the N-atom vacancy on the electronic transport properties of the devices. The results indicate that N-1, N-2, N-3, N-12, N-23, N-123, N-1234, and N-12345 model devices did not change the high anisotropy and NDR effect of the device, and among them the N-1234 exhibits the strongest anisotropy, the I Z/I A reaches 6.12. A significant NDR effect is also observed for the electronic transport along the armchair direction in these devices. However, the current gradually decreases as an increase of the number of N defects. These findings showcase the considerable potential for integration of the CoN4C2 monolayer in switching devices and NDR-based multifunctional nanodevices.

Size- and Voltage-Dependent Electron Transport of C2N-Rings-Based Molecular Chains.

C2N-ring-based molecular chains were designed at the molecular level and theoretically demonstrated to show distinctive and valuable electron transport properties that were superior to the parent carbonaceous system and other similar nanoribbon-based molecular chains. This new -type molecular chain presented an exponential attenuation of the conductance and electron transmission with the length. Essentially, the molecular chain retained the electron-resonant tunneling within 7 nm and the dominant transport orbital was the LUMO. Shorter molecular chains with stronger conductance anomalously possessed a larger tunnel barrier energy, attributing to the compensation of a much smaller HOMO-LUMO gap, and these two internal factors codetermined the transport capacity. Some influencing factors were also studied. In contrast to the common O impurity with a tiny effect on electron transmission of the C2N rings chain, the common H impurity clearly improved it. When the temperature was less than 400 K, the electron transmission varied with temperature within a narrow range, and the structural disorder deriving from proper heating did not greatly modify the transmission possibility and the exponentially decreasing tendency with the length. In a non-equilibrium condition, the current increased overall with the bias but the growth rate varied with size. A valuable negative differential resistance (NDR) effect appeared in longer molecular chains with an even number of big carbon-nitrogen rings and strengthened with size. The emergence of such an effect originated from the reduction in transmission peaks. The conductance of longer molecular chains was enhanced with the voltage but the two shortest ones presented completely different trends. Applying the bias was demonstrated to be an effective way for C2N-ring-based molecular chains to slow down the conductance decay constant and affect the transport regime. C2N-ring-based molecular chains show a perfect application in tunneling diodes and controllable molecular devices.

Metallaaromatic Complexes as Candidates for Future Molecular Materials and Electronic Devices: Recent Advancements.

In recent years, the field of organometallic chemistry has made a great progress and diverse types of metallaaromatics have successively been reported. In those studies, incorporation of ligated osmium centers into metallaaromatic systems played a prominent role. The reviewed literature documents that certain metallaaromatics with unconventional photophysical properties, redox and electronic transport properties and magnetism, have potential to be widely used in diverse practical applications, with selected examples of amino acid and fluoride anion identification, photothermal effects, functional materials, photodynamic therapy (PDT) in biomedicine, single-molecule junction conductors, and electron-transport layer materials (ETLs) in solar cells.

Investigating the molecular crystals of L-Alanine, DL-Alanine, β-Alanine, and Alanine hydrogen chloride: Experimental and DFT analysis of structural and optoelectronic properties

In this study, DFT calculations were employed to assess and contrast the structural, electronic, and optical characteristics of five alanine crystal forms. The Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) with the Tkatchenko-Scheffler dispersion correction scheme was employed and compared to the PBE functional and the local density approximation (LDA) without dispersion correction. Experimentally, alanine crystal powders were characterized through X-ray diffraction (XRD) and UV–VIS absorption spectrum. Additionally, UV–VIS absorption measurements were performed on L-α-alanine, DL-alanine, β-alanine, and alanine hydrochloride solvated in water. Significant deviations (>10%) were observed between the experimental crystal lattice parameters and those predicted by the GGA and LDA methods. Incorporating dispersion correction into the GGA functional improved prediction accuracy. Additionally, time-dependent DFT (TD-DFT) computations using the polarizable continuum model were conducted to analyze the UV/VIS absorption spectrum of α-, β-, DL-, and hydrogen chloride alanine in water and interpret experimental data. Different alanine crystals exhibited substantial anisotropic electronic and optical properties, including effective masses, absorption, and dielectric function. The L-α-HCl structure displayed the smallest band gap (4.67 eV), suggesting its suitability for applications such as L-α/L-α-HCl/L-α quantum well structures. The main effective masses of electrons and holes were also determined for each crystal for a better understanding of their electronic transport properties.

Optimizing thickness of tin oxide electron transporting layer to reduce hysteresis in carbon-based perovskite solar cells

Tin oxide (SnO2) is frequently chosen as an electron transport layer (ETL) in perovskite solar cells (PSCs) owing to its outstanding electron transport properties. Nevertheless, the thickness of the ETL significantly influences hysteresis behavior of PCSs. To address this issue, tin (II) 2-ethylhexanoate in 2-methoxyethanol (2-MOE) was employed as the precursor solution for SnO2 ETL preparation. We systematically varied its concentrations from 0.2 M to 1.0 M to optimize the film thickness. Our findings indicate that the PSC with a SnO2 film deposited from a 0.6 M precursor concentration achieved the highest power conversion efficiency (PCE) of 13.51% and the lowest hysteresis index (HI) of 0.54. Furthermore, we explored the impact of film thickness on hysteresis behaviour and provided a comprehensive analysis. Based on the experiment, it was observed that the thickness of the film has an impact on the presence of defects and interfacial charge transfer, which could contribute to the occurrence of HI. This study offers valuable insights into the development of alternative ETLs suitable for large-scale PSC production.

A DFT study of quantum electronic transport properties of InTeCl

A DFT study of quantum electronic transport properties of InTeCl

A comparative study on the surface chemistry and electronic transport properties of Bi2Te3 synthesized through hydrothermal and thermolysis routes

Bismuth telluride-Bi2Te3 is the most promising material for harvesting thermal energy near room temperature. There are numerous works on Bi2Te3 reporting significantly different transport properties, with no clear connection to the synthetic routes used and the resultant surface chemistry of the synthesized materials. It is of utmost importance to characterize the constituent particles’ surface and interfaces to get a better understanding of their influence on the transport properties, that will significantly improve the material design starting from the synthesis step. Electrophoretic deposition (EPD) is a promising technique, enabling the formation of thick films using colloidally stabilized suspensions of pre-made nanoparticles, which can enable the study of the effect of surface chemistry, in connection to the synthetic route, on the material’s transport properties. In order to explore the differences in surface chemistry and the resultant transport properties in relation to the synthetic scheme used, here we report on Bi2Te3 synthesised through two wet-chemical routes in water (Hydro-) and oil (Thermo-) as the solvents. XRD analysis showed a high phase purity of the synthesized materials. SEM analysis revealed hexagonal platelet morphology of the synthesized materials, which were then used to fabricate EPD films. Characterization of the EPD films reveal significant differences between the Hydro- and Thermo-Bi2Te3 samples, leading to about 8 times better electrical conductivity values in the Thermo-Bi2Te3. XPS analysis revealed a higher metal oxides content in the Hydro-Bi2Te3 sample, contributing to the formation of a resistive layer, thus lowering the electrical conductivity. Arrhenius plots of electrical conductivity vs inverse temperature was used for the estimation of the activation energy for conduction, revealing a higher activation energy need for the Hydro-Bi2Te3 film, in agreement with the resistive barrier oxide content. Both the samples exhibited negative Seebeck coefficient (S) in the order of 160–170 mV/K. The small difference in S of Hydro- and Themo-Bi2Te3 films was explained by the effective medium theory, revealing that the magnitude of S is linearly correlated with the surface oxide content. Based on the findings, TE materials synthesized through thermolysis route is recommended for further studies using soft treatment/processing of pre-made TE materials. EPD platform presented here is shown to clearly expose the differences in the electronic transport in connection to nanoparticle surface chemistry, proving a promising methodology for the evaluation of morphology, size and surface chemistry dependence of electronic transport for a wide range of materials.

Role of morphology and composition in the transport properties of highly conducting CVD grown PtTex

Platinum telluride (PtTex), a metallic noble transition-metal dichalcogenide, has emerged as a central candidate for magnetic and optoelectronic applications. Recently, PtTex has drawn great attention because of its large positive magnetoresistance and broadband photodetection owing to its astounding electron transport properties. Here, we report the role of morphology, texture, and composition in the transport properties of CVD-grown highly conducting PtTex. Two different compositions of Te atoms, named tellurium stoichiometric (TS) and tellurium rich (TR), with different morphology have been obtained in the PtTex films. The highest longitudinal conductivity was found to be ∼ 3.57 × 107 and 3.83 × 106 S m−1 at 200 K in the TR and TS-PtTex samples, respectively. The maximum carrier density in TR and TS-PtTex samples was found to be of the order of 1022 and 1021 cm−3, respectively. Further, the negative magnetoresistance has also been found to be ∼ −2.2% at 300 K in the presence of an in-plane magnetic field of 9 T. Our results, reporting extremely high conductivity along with negative magnetoresistance, promise exciting applications of PtTex for nanoelectronic devices.

Utilizing Se vacancies as electronic traps to synergize impedance matching and dipole polarization with ultrathin strategy to boost Fe-Se electromagnetic wave absorption

The electronic structure, transport properties and magnetic properties of the material can be adjusted by regulating the formation and concentration of anionic vacancies. In particular, materials based on transition metal chulides (TMC) have high second-order nonlinearity and atomic thin thickness, and anionic vacancy engineering can effectively achieve the optimization of material properties. However, the impact of anion vacancy engineering on dipole polarization has not been fully resolved and clarified yet, and it cannot be solely relied upon semi-empirical methods. Therefore, it is of utmost importance to deeply understand the intrinsic mechanism between vacancies and electromagnetic (EM) parameters. This knowledge will provide crucial guidance for the development of advanced electromagnetic wave (EMW) absorption materials. In this study, a novel approach is proposed for the first time, which involves the creation of Se vacancies at the heterogeneous interface formed by Fe-Se compounds. Remarkably, the generation of Se vacancies leads to an increased electron transfer from Fe to Se atoms, resulting in the formation of numerous dipolarization centers. This effect significantly enhances the material’s polarization loss capacity. Furthermore, the presence of Se vacancies acts as traps for nearby free electrons, reducing the material’s conductivity, weakening the skin effect, and improving impedance matching. The precise modulation of Se vacancies in Fe-Se compounds has led to the achievement of ultrathin characteristics and significantly enhanced EM absorption capabilities. With a thickness of only 1.5 mm, the effective absorption bandwidth (EAB) reaches 5.42 GHz, covering the Ku band, which represents a remarkable increase of 53.5 % compared to unmodified Fe-Se compounds. At a thickness of 1.3 mm, the minimum reflection loss (RL) reaches −42.4 dB, demonstrating an impressive improvement of 41.3 %. Moreover, simulations of the radar cross section (RCS) indicate that the material possesses a robust microwave attenuation ability, underscoring its great potential for practical applications.

Electron-Transporting Properties and Ultrasmall Band Gap of BODIPY-Based Conjugated Polymers: Teach an Old Dog New Tricks

Electron-Transporting Properties and Ultrasmall Band Gap of BODIPY-Based Conjugated Polymers: Teach an Old Dog New Tricks

Sum-frequency generation and amplification processes in semiconductor superlattices

Semiconductor superlattices are very well-known structures due to their specific electron transport properties, making them extremely attractive to be employed in electronic or optoelectronic devices. The interest in such structures has been recently additionally stirred up due to the first successful experimental demonstration of parametric gain in GaAs/AlGaAs superlattices, resulting in the generation of harmonics, half-harmonics and fractional harmonics. This invention paves the way for a successful realization of superlattice-based generators and amplifiers up to the terahertz frequency range. Despite the emerging experimental results and decade-long theoretical research, unresolved aspects, related to the physical processes inside the superlattices, persist. Lately, the biasing effect was extensively analysed for the case of degenerate processes in the superlattice; however, the non-degenerate case was left out of frame until now. Within this research, we further expand the boundaries of previous investigation by exploring the differences of non-degenerate processes. The study uncovers the asymmetry appearance of the probe field vs. relative phase dependences as well as the possibility of parametric fractional frequency generation. Finally, the concept of energy reflow between two participating probes is predicted and discussed.

Highly reduced efficiency roll-off with 5,9-dioxa-13b-boranaphtho[3,2,1-de]anthracen-containing unit on bipolar host for improved OLEDs device lifespan

The electrical, thermal, and optical properties of the host material used in the light-emitting layer of a thermally activated delayed fluorescence organic light-emitting diode (TADF-OLED) directly affect its efficiency, lifetime, and color. In this study, a new host material was designed, synthesized, and then applied to a green TADF-OLED device to evaluate its performance as a host. The host material was designed in a bipolar configuration, ensuring the balanced introduction and transport of electrons and holes. This balance was achieved by incorporating a carbazole unit to facilitate hole injection and transport. Moreover, a 5,9-dioxa-13b-boranaphtho [3,2,1-de]anthracene (DOBNA) unit containing a boron atom was introduced for electron injection and transport. These units were linked to ortho terphenyl spacers. The DOBNA unit improved the electron transport properties, the thermal stability of molecule, and anionic bond dissociation energy. Consequently, the device evaluated using the DOBNA-introduced material as a host for 4CzIPN, a TADF dopant, enhanced the performance by ∼ four times from LT80@1000 nit to 15.1 h compared to the unipolar host material comprising carbazole and ortho-terphenyl.

Effective thermo-electric-mechanical modeling of capacitively coupled plasma in low-pressure conditions: Modeling and application in dry etching

In semiconductor dry etching process, capacitively coupled plasma (CCP) is widely used in low-pressure environments. However, the kinetics of species particles in low-pressure conditions are different from the general environments. Traditional continuum models are popular in industry due to their simplicity, but they struggle to account for the kinetics of particles in low-pressure conditions. Although particle-in-cell (PIC) modeling is suitable for simulating the behavior of a single particle, it is difficult to perform such industrial simulations due to the high computational cost. To account for both kinetics and engineering applicability, this study presents an effective thermo-electric-mechanical modeling structure of CCP at low-pressure conditions. This modeling structure includes balance laws of continua derived from the global energy equilibrium containing thermal, electric and mechanical energies. The ion momentum, which is ignored in traditional plasma continuum models, is considered in the balance laws, and electron energy distributions are obtained by solving the Boltzmann equation to obtain the properties of electron transport. In addition, the model variables are calculated based on mixed kinetic theory accounting for the fraction of each species. The results of the proposed modeling are compared to those of a PIC model to validate its ability to describe the distribution of electrons with respect to pressure conditions. Based on the proposed numerical formulations, this study built a MATLAB-based program to guide the design of a screen baffle in dry etching equipment. This program captures the critical aspects of the practical application of screen baffle design in the context of the dry etching process. The results of this paper showed that the proposed model can be applied to engineering applications under low-pressure conditions.