P-type Metal Oxide Research Articles

Wideband Phase-Compensated VGA with PMOS Switch in 40-nm CMOS for 120-GHz Band

This paper presents a 120-GHz wideband phase-compensated variable gain amplifier (VGA) with a p-type metal–oxide–semiconductor (PMOS) switch using a 40-nm CMOS process. By applying a PMOS switch to the common source (CS) amplifier, the gain of the CS amplifier can be controlled by as much as 6.1 dB with 2° phase variations in 15.1-GHz bandwidth ranging from 100.9 to 115 GHz. The measured gain and 3-dB bandwidth of the VGA are 19.1 dB and 33.8 GHz for high-gain state, and 13 dB and 44.2 GHz for low gain state, respectively. Meanwhile, the DC power consumption in the high-gain state is 45 mW, and the OP1dB is −2.7 dBm.

Decoration of CuO NWs Gas Sensor with ZnO NPs for Improving NO2 Sensing Characteristics.

This paper introduces a method for improving the sensitivity to NO2 gas of a p-type metal oxide semiconductor gas sensor. The gas sensor was fabricated using CuO nanowires (NWs) grown through thermal oxidation and decorated with ZnO nanoparticles (NPs) using a sol-gel method. The CuO gas sensor with a ZnO heterojunction exhibited better sensitivity to NO2 gas than the pristine CuO gas sensor. The heterojunction in CuO/ZnO gas sensors caused a decrease in the width of the hole accumulation layer (HAL) and an increase in the initial resistance. The possibility to influence the width of the HAL helped improve the NO2 sensing characteristics of the gas sensor. The growth morphology, atomic composition, and crystal structure of the gas sensors were analyzed using field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy, and X-ray diffraction, respectively.

Design and Simulation of Metal Oxide Gas Sensor for Breath Analyzer Application

Metal oxide semiconductor has been widely used for breath analyzer applications. In this work, Acetone gas is the target gas as it an important breath marker for diabetes disease. Among the different p-type metal oxide nanostructures, Nickel oxide nanospheres are used as the sensing material as it is a promising candidate for Acetone sensing. The variation of resistance of the sensing material with the concentration of the target gas was analyzed. As Acetone is a reducing gas, the resistance of the sensing layer was found to increase when the sensing layer was exposed to the target gas. The simulation was done using COMSOL Multiphysics.

MOF-derived synthesis of Co3O4 nanospheres with rich oxygen vacancies for long-term stable and highly selective n-butanol sensing performance

Long-term stability and selectivity are crucial for the practical application of gas sensors, which are closely related to the microstructure and composition of sensor materials. In this work, Co-based metal organic framework (MOF) is used as a precursor and prepared by a simple hydrothermal method. After calcination, a series of Co3O4 nanospheres with various microstructures are derived. When the calcination temperature increases from 300 °C to 500 °C, the microstructure of Co3O4 nanospheres changed from rough solid to porous, and then transformed into porous core-shell. When assembled into the gas sensors, the Co3O4 nanospheres with porous structure calcined at 400 °C (Co3O4-400) show the highly selective response of 53.78 for 100 ppm n-butanol at the operating temperature of 140 °C. Moreover, the theoretical limit of detection was calculated to be 150 ppb. The reproducibility, selectivity and stability of the gas sensor were further verified to be excellent. After 45 days, the response value of Co3O4-400 is at 86.74%, even after 75 days, the response value remains at 74.93%. The main reason can be attributed to the large specific surface area, abundant pore structure and a large number of oxygen vacancies on its surface. These findings provide reference for the development of p-type metal oxide semiconductor (MOS) sensors with long-term stability and high performance.

Ultra-High Boron Doping of Si and Ge for Nanoelectronics and Photonics

In-situ boron doping of Si and Ge can be of use in various types of devices. Poly-Si:B gates can be integrated in p-type metal oxide semiconductor (pMOS) transistors. Monocrystalline Si:B layers can be used in p-i-n junctions for RF switches, attenuators, photo-detectors (PDs) or phase shifters. Ge:B layers can be integrated in the sources and drains of Ge pMOS transistors or as the p-type films in Ge p-i-n PDs. If the growth temperature is low enough, they can even be used in GeSn PDs or light emitting devices. We have explored here the boron-doping of Si and Ge with Si2H6 + B2H6 and Ge2H6 + B2H6. Such chemistries enable Si (Ge) epitaxy at temperatures lower than with conventional SiH4 (GeH4) precursors. Growth temperatures and pressures in our 200mm RP-CVD tool were 550°C, 20 Torr (Si) and 350°C, 100 Torr (Ge).X-Ray Diffraction (XRD) was used to convert the tensile strain in Si:B or Ge:B into substitutional B concentrations, as shown in Fig. 1 and Fig. 2, with layer peaks moving away from the Si(001) substrate or the Ge Strain-Relaxed Buffers (SRB) as the diborane flow increased. The presence of marked thickness fringes testified to the high crystalline quality of the films. Secondary Ions Mass Spectrometry (SIMS) gave us the atomic B concentration. X-Ray Reflectivity on Si0.5Ge0.5 / Si:B stacks yielded Si:B Growth Rates (GR). Finally, differential weighting gave us the thickness of Ge:B layers grown on Ge SRBs and other GR values.A huge Si:B GR increase, from 9.5 up to 40 nm min.-1, was evidenced when adding relatively small amounts of B2H6 to Si2H6, as shown in Fig. 3. This was due to the presence of B atoms on the surface which catalyzed H desorption, freeing sites for growth. Ultra-high substitutional and atomic boron contents were obtained in those Si:B layers (at most: 2.7x1020 and 1.1x1021 atoms cm-3), as shown in Fig. 4. Films became poly-cristalline for the highest F(B2H6)/F(Si2H6) Mass-Flow Ratios (MFRs) probed, without XRD peaks anymore and a boron ion concentration which was reduced compared to its peak value of 2x1020 cm-3. The good agreement between substitutional, atomic and ionic B concentrations for low to medium MFRs is to be underlined. By contrast, the growing discrepancy between XRD and SIMS for the highest diborane flows probed might partly be due to a SIMS artefact. Indeed, the Relative Sensistivity Factor used to convert the raw SIMS signals into B concentrations was for doped layers and not higher boron content binary alloys. The presence of B atoms in nanoclusters that did not contribute to XRD cannot be excluded, however.A definite growth rate increase (from 6 up to 21 nm min.-1) and really high substitutional B concentrations (at most: 4.8x1020 atoms cm-3) were also obtained for Ge:B, as shown in Fig. 5 and Fig. 6. The good agreement between XRD and SIMS for medium F(B2H6)/F(Ge2H6) MFR is to be underlined. The growing discrepancy for high diborane flows might be due to the same SIMS artifact as before and to the presence of B atoms in nanoclusters. x/(1-x) = m*F(B2H6)/F(Si2H6 or Ge2H6) relationships accounted for the semi-linear increase of the substitutional or atomic B concentration x with the diborane flow, with (i) msubst. = 1.85 (matom. = 7.45) in Si:B and (ii) msubst. = 0.15 (matom. = 0.68) in Ge:B. m values above 1 meant that B incorporation was easier than Si incorporation in Si:B. In contrast, B incorporation was more difficult than Ge incorporation in Ge:B alloys, as m was less than 1, then.Current growth rate increases and B concentrations are definitely higher than with mainstream chemistries. For Si:B grown at 650°C, 20 Torr with SiH4 + B2H6, we had for instance GR increases from 9 up to 23 nm min.-1, with at most 9x1019 cm-3 B ions concentrations before layers became poly-crystalline (ECS Trans. 16 (10), 485 (2008)). For Ge:B grown at 400°C, 100 Torr with SiH4 + B2H6, GR increased from 10 up to 18 nm min.-1, with at most 1020 cm-3 B ions concentrations (Thin Solid Films 557, 4 (2014)). The advantages of switching over to higher order Si and Ge precursors and adopting lower growth temperatures are obvious. Figure 1

Low-temperature processed bipolar metal oxide charge transporting layers for highly efficient perovskite solar cells

Metal oxide charge carrier transporting materials have been incorporated in many ways in perovskite solar cells (PSCs) because of their excellent chemical stability, wide band gaps, and reasonable mobilities. Herein, we report a low-temperature solution-processed intercalation method for introducing metal oxides displaying bipolar transporting capability into PSCs. We intercalated p-type nickel oxide (NiO) with cesium carbonate (Cs2CO3) to function as hole and electron transport layers for inverted (p–i–n) and conventional planar (n–i–p) PSCs, respectively. When compared with the corresponding NiO-only hole transporting layer, the Cs2CO3-intercalated NiO layer displayed enhanced electron extraction without sacrificing its hole extraction capability. The power conversion efficiencies of the inverted and conventional planar PSCs reached as high as 12.08 and 13.98%, respectively. This approach not only realizes the bipolar extraction capacity of Cs2CO3-intercalated p-type metal oxides but also opens up a possible route for preparing interconnecting layers for tandem optoelectronics.

Study of physical properties of chemical bath deposited nickel oxide thin films

Abstract Being the p-type metal oxide semiconductor, nickel oxide (NiO) has gained lots of interest due to its interesting properties towards various applications. Here, the emphasis has been studying the force of attraction between the contact points of deposited thin film and its substrate using adhesion measurements. Initially the chemical bath deposited nickel (Ni) films on glass substrates were synthesized and further oxidized in air at 300 °C for 2 h to get the NiO thin films. The structural and morphological studies of Ni and NiO films were undertaken using XRD and SEM respectively. The crystal structure of NiO was confirmed with (1 1 1), (2 0 0), (2 2 0) peaks. The flakes like surface morphology was observed. The oxidized thin films showed higher adhesion than the metal thin films. The effect of deposition time on adhesion was also studied.

Organic Chromophores Designed for Hole Injection into Wide-Band-Gap Metal Oxides for Solar Fuel Applications

The power conversion efficiency of tandem dye-sensitized photoelectrosynthesis cells is limited by the number of p-type metal oxide semiconductors and chromophores available for the photocathode. H...

Ultra-High Boron Doping of Si and Ge for Nanoelectronics and Photonics

Si:B or Ge:B layers can used to fabricate devices such as p-type metal oxide semiconductor transistors, photo-detectors, light emitting diodes and so on. We have explored here the in-situ boron-doping of Si and Ge with Si2H6 + B2H6 and Ge2H6 + B2H6. Such chemistries enable Si or Ge epitaxy at temperatures definitely lower than with mainstream precursors such as SiH4 or GeH4. Growth temperatures and pressures in our 200mm Reduced Pressure - Chemical Vapor Deposition tool were 550°C, 20 Torr (Si) and 350°C, 100 Torr (Ge). X-ray Diffraction was used to convert the tensile strain in Si:B or Ge:B layers into substitutional B concentrations, while Secondary Ions Mass Spectrometry gave us the atomic B concentration. As far as Si:B was concerned, a huge growth rate increase (from 9.5 up to 39.8 nm min.-1) was evidenced when adding relatively small amounts of B2H6 to Si2H6. Ultra-high substitutional and atomic boron contents were obtained in those Si:B layers (at most: 2.7x1020 and 1.1x1021 atoms cm-3). For higher B2H6 flows, films became poly-crystalline. A similar growth rate increase (from 5.8 up to 20.8 nm min.-1) and really high substitutional B concentrations (at most: 4.8x1020 atoms cm-3) were otherwise obtained for Ge:B. Such concentrations were several times higher than with conventional chemistries.

Reversible Electron Doping of Layered Metal Hydroxide Nanoplates (M = Co, Ni) Using n-Butyllithium

Ambipolar doping of metal oxides is critical toward broadening the functionality of semiconducting oxides in electronic devices. Most metal oxides, however, show a strong preference for a single doping polarity due to the intrinsic stability of particular defects in an oxide lattice. In this work, we demonstrate that layered metal hydroxide nanomaterials of Co and Ni, which are intrinsically p-doped in their anhydrous rock salt form, can be n-doped using n-BuLi as a strong electron donor. A combination of X-ray characterization techniques reveal that hydroxide vacancy formation, Li+ adsorption, and varying degrees of electron delocalization are responsible for the stability of injected electrons. The doped electrons induce conductivity increases of 4-6 orders of magnitude relative to the undoped M(OH)2. We anticipate that chemical electron doping of layered metal hydroxides may be a general strategy to increase carrier concentration and stability for n-doping of intrinsically p-type metal oxides.

Printed Logic Gates Based on Enhancement- and Depletion-Mode Electrolyte-Gated Transistors

Electrolyte-gated thin-film transistors (EGTs) with indium oxide channel, and expected lifetime of three months, enable low-voltage operation (~1 V) in the field of printed electronics (PEs). The channel width of our printed EGTs is varied between 200 and 1000 μm, whereas a channel length between 10 and 100 μm is used. Due to the lack of uniform performance p-type metal oxide semiconductors, n-type EGTs and passive elements are used to design circuits. For logic gates, transistor-resistor logic has been employed so far, but depletion and enhancement-mode EGTs in a transistor-transistor logic boost the circuit performance in terms of delay and signal swing. In this article, the threshold voltage of the EGT, which determines the operation mode, is tuned through sizing of the EGTs channel geometry. The feasibility of both transistor operation modes is demonstrated for logic gates and ring oscillators. An inverter operating at a supply voltage of 1 V shows a maximum gain of 9.6 and a propagation delay time of 0.7 ms, which represents an improvement of ~ 2x for the gain and oscillation frequency, in comparison with the resistor-transistor logic design. Moreover, the power consumption is reduced by 6x.

Generalized Synthesis to Produce Transparent Thin Films of Ternary Metal Oxide Photoelectrodes.

Developing facile approaches to prepare non-light-scattering ternary oxide thin film photoelectrodes is an important goal for solar water splitting tandem cells. Herein, a novel synthesis route is reported that employs ethylenediaminetetraacetic acid (EDTA) to enable compatible water solubility of diverse metal cations, which affords transparent films by solution processing. By using BiVO4 as a model material, a remarkable improvement in transparency is demonstrated, quantified by the direct transmittance at 600 nm of >80 % versus the <10 % observed with state-of-the-art electrodeposited thin films while maintaining reasonable solar-driven oxidation photocurrents (1.75 mA cm-2 in the presence of a sulfite hole scavenger). Furthermore, it is demonstrated that the synthesis technique can be applied in a general fashion towards the synthesis of diverse n- and p-type metal oxide materials, such as ZnFe2 O4 and CuFeO2 .

Recent Advances in Heteroatom Doped Graphitic Carbon Nitride (g-C3N4) and g-C3N4/Metal Oxide Composite Photocatalysts

Industrial wastewater contains abundant organic dyes, antibiotics, pesticides, chemical fertilizers or heavy metal ions, which seriously deteriorate the ecological environment. Among the practical techniques for reducing water pollution, photocatalysis is a kind of sustainable solar energy conversion technique for removing organic contaminants. In this review, the advances in the preparation, modification, and doping of graphitic carbon nitride (g-C3N4), including non-metal doping, metal doping, dual- or tri-doping, are introduced firstly. Then, we systematically reviewed the recent progress of g-C3N4/metal oxide composite photocatalysts, including a g-C3N4/n-type metal oxide, such as TiO2, ZnO, SnO2, WO3, FexOy, CeO2, V2O5, MoO3, MnO2, Nb2O5, In2O3, and a g-C3N4/p-type metal oxide, such as Co3O4, Bi2O3, NiO and Cu2O. At last, we summarized the design principles for preparing heteroatom doped g-C3N4 and g-C3N4/metal oxide composites, and forecast the promising research directions. The main objective is to provide a guideline for designing highperformance heteroatom doped g-C3N4 and g-C3N4/metal oxide photocatalysts.

Nickel oxide for inverted structure perovskite solar cells

The emergence of inverted perovskite solar cells (PSCs) has attached great attention derived from the potential in improving stability. Charge transporting layer, especially hole transporting layer is crucial for efficient inverted PSCs. Organic materials were used as hole transporting layer previously. Recently, more and more inorganic hole transporting materials have been deployed for further improving the device stability. Nickel oxide (NiO x ) as p-type metal oxide, owning high charge mobility and intrinsic stability, has been widely adopted in inverted PSCs. High performance over 20% efficiency has been achieved on NiO x base inverted PSCs. Herein, we have summarized recent progresses and strategies on the NiO x based PSCs, including the synthesis or deposition methods of NiO x , doping and surface modification of NiO x for efficient and stable PSCs. Finally, we will discuss current challenges of utilizing NiO x HTLs in PSCs and attempt to give probable solutions to make further development in efficient as well as stable NiO x based PSCs. Nickel oxide is a promising hole transporting material for stable perovskite solar cells. However, the low electric conductivity and the mismatched energy level alignment of NiO x have restricted the efficiency of NiO x based device. Doping and surficial modification are considered key measures to address these drawbacks. This review systematically sorts out the effective strategies for improving NiO x in recent years and gives a future outlook.

Random telegraph signals caused by a single dopant in a metal–oxide–semiconductor field effect transistor at low temperature

While the importance of atomic-scale features in silicon-based device for quantum application has been recognized and even the placement of a single atom is now feasible, the role of a dopant in the substrate has not attracted much attention in the context of quantum technology. In this paper, we report random telegraph signals (RTSs) originated from trapping and detrapping of an electron by a donor in the substrate of a p-type metal–oxide–semiconductor field-effect-transistor. RTSs, not seen when the substrate was grounded, were observed when a positive bias was applied to the substrate. The comprehensive study on the signals observed reveals that the nature of the RTSs is discrete threshold voltage variations due to the change in the depletion layer width depending on the charge state of a single dopant, neutral or positively charged.

Novel Hybrid Silicon SETMOS Design for Power Efficient Room Temperature Operation

A novel hybrid silicon Single Electron Transistor Metal Oxide Semiconductor (SETMOS) logic is evaluated for its functionality and usability. Emphasis is given on obtaining functionality at ambient temperature with low power consumption and significant drive. Performance is evaluated with respect to 22 nm Complementary Metal Oxide Semiconductor (CMOS) technology and other popular hybrid SETMOS topologies. The results produced here not only comprehend performance of various SET-CMOS based logic architectures, but they are also closer to real values as they consider effect of parasitic in respective topologies. Proposed work is power efficient, scalable, accurate and process compatible logic design, which uses less hardware and operates at room temperature. It relies on CMOS compatible fabrication of Silicon SET and P-Type Metal Oxide Semiconductor (PMOS) on same chip footprint. When compared with contemporary SETMOS hybrid circuits, it offers 90.29 % power improvement at the cost of 16.53 % reduction in speed.

Statistical analysis of the impact of charge traps in p-type MOSFETs via particle-based Monte Carlo device simulations

In this paper, statistical analysis of the static impact of charge traps on the drain current of p-type metal–oxide–semiconductor field-effect transistors is presented. The study was carried out by employing a 3-D particle-based Monte Carlo device simulator, which is capable of accounting for the interplay between charge traps and the random dopant fluctuation effect. It was observed that the impact of a single charged trap on the transistor’s on-current is strongly dependent on the trap position along the channel length, on trap depth into the gate oxide, and on the trap position along the channel width. The current deviation estimated from statistical simulations is shown to be exponentially distributed, in agreement with experimental data from the literature. Results are also compared with uniform channel theory predictions.

Design of PMOS and NMOS Input Folded Cascode Amplifier using 180nm SCL Technology Node for Low Power Application

This paper presents the details design and simulation of the Folded Cascode amplifier using Source-Coupled-Logic (SCL) technology node for both the P-Type Metal Oxide Semiconductor (PMOS) and N-Type Metal Oxide Semiconductor (NMOS) input. The different way to implement the circuit design for a given specification has clearly described including all the design equation has been presented. All the parameter like open loop gain, Unity Gain Bandwidth (UGB) and Phase Margin (PM) are compared for both the NMOS and PMOS input fully differential folded cascode op-amp circuit are discussed and finally we have got after performance analysis that NMOS input fully differential folded cascode op-amp is the best choice for low power high speed application like in pipeline Analog to Digital (ADC). The circuit has been simulated using cadence virtuoso tool in 0.18μm SCL technology node.

High Responsivity and External Quantum Efficiency Photodetectors Based on Solution-Processed Ni-Doped CuO Films.

Photodetectors based on p-type metal oxides are still a challenge for optoelectronic device applications. Many effects have been paid to improve their performance and expand their detection range. Here, high-quality Cu1-xNixO (x = 0, 0.2, and 0.4) film photodetectors were prepared by a solution process. The crystal quality, morphology, and grain size of Cu1-xNixO films can be modulated by Ni doping. Among the photodetectors, the Cu0.8Ni0.2O photodetector shows the maximum photocurrent value (6 × 10-7 A) under a 635 nm laser illumination. High responsivity (26.46 A/W) and external quantum efficiency (5176%) are also achieved for the Cu0.8Ni0.2O photodetector. This is because the Cu0.8Ni0.2O photosensitive layer exhibits high photoconductivity, low surface states, and high crystallization after 20% Ni doping. Compared to the other photodetectors, the Cu0.8Ni0.2O photodetector exhibits the optimal response in the near-infrared region, owing to the high absorption coefficient. These findings provide a route to fabricate high-performance and wide-detection range p-type metal oxide photodetectors.

Hierarchical NiCo2O4 microspheres assembled by nanorods with p-type response for detection of triethylamine

The morphological and structural design provides an efficient protocol to optimize the performance of gas sensing materials. In this work, a gas sensor with high sensitivity for triethylamine (TEA) detection is developed based on p-type NiCo2O4 hierarchical microspheres. The NiCo2O4 microspheres, synthesized by a hydrothermal route, have a three-dimensional (3D) urchin-like structure assembled by nanorod building blocks. The structure-property correlation has been investigated by powder X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscope, scanning electron microscope, N2 adsorption-desorption tests and comprehensive gas sensing experiments. The influence of calcination temperature on the morphological structure and sensing performances has been investigated. Results reveal that the material annealed at 300 °C has a very large specific surface area of 125.27 m2/g, thereby demonstrating the best TEA sensing properties including high response and low limit of detection (145 ppb), good selectivity and stability. The further increase of the calcination temperature leads to the collapse of the 3D hierarchical structure with significantly decreased surface area, which is found to decline the sensing performances. This work indicates the promise of ternary p-type metal oxide nanostructures for application in highly sensitive gas sensors.