Search query: P type semiconductor

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abstract: Photoelectric detectors are the central part of modern photodetection systems with numerous commercial and scientific applications. p Type semiconductor materials play important roles in optoelectronic devices. Photodetectors based on p type semiconductor materials have attracted a great deal of attention in recent years because of their unique properties. Here, a comprehensive summary of the recent progress mainly on photodetectors based on inorganic p type semiconductor materials is presented. Various structures, including photoconductors, phototransistors, homojunctions, heterojunctions, p i n junctions, and metal semiconductor junctions of photodetectors based on inorganic p type semiconductor materials, are discussed and summarized. Perspectives and an outlook, highlighting the promising future directions of this research field, are also given.
author_names: Feng Teng

Kai Hu

Weixin Ouyang

Xiaosheng Fang
title: Photoelectric Detectors Based on Inorganic p Type Semiconductor Materials.
venue: Advanced materials
year: 2018

abstract: Development of high performance p type semiconductor based gas sensors exhibiting fast response/recovery times with ultra high response are of major importance for gas sensing applications. Recent reports demonstrated the excellent properties of p type semiconducting oxide for various practical applications, especially for selective oxidation of volatile organic compounds (VOCs) In this work, sensors based on CuO nanowire (NW) networks have been successfully fabricated via a simple thermal oxidation process on pre patterned Au/Cr pads. Our investigation demonstrates high impact of the process temperature on aspect ratio and density of copper oxide NWs. An optimal temperature for growth of thin and densely packed NWs was found to be at 425 degrees C. The fabricated sensors demonstrated ultra high gas response by a factor of 313 to ethanol vapour (100 ppm) at an operating temperature of 250 degrees C. High stability and repeatability of these sensors indicate the efficiency of p type oxide based gas sensors for selective detection of VOCs. A high performance nanodevice was fabricated in a FIB SEM system using a single CuO NW, demonstrating an ethanol response of 202 and rapid response and recovery of similar to 198 ms at room temperature. The involved gas sensing mechanism of CuO NW networks has been described. We consider that the presented results will be of a great interest for the development of higherperformance p type semiconductor based sensors and bottomup nanotechnologies. (C) 2016 WILEY VCH Verlag GmbH Co. KGaA, Weinheim
author_names: Oleg Lupan

Vasile Postica

Vasilii Cretu

Niklas Wolff

Viola Duppel

Lorenz Kienle

Rainer Adelung
title: Single and networked CuO nanowires for highly sensitive p type semiconductor gas sensor applications
year: 2016

abstract: This review reports the properties of p type semiconductors with nanostructured features employed as photocathodes in photoelectrochemical cells (PECs) Light absorption is crucial for the activation of the reduction processes occurring at the p type electrode either in the pristine or in a modified/sensitized state. Beside thermodynamics, the kinetics of the electron transfer (ET) process from photocathode to a redox shuttle in the oxidized form are also crucial since the flow of electrons will take place correctly if the ET rate will overcome that one of recombination and trapping events which impede the charge separation produced by the absorption of light. Depending on the nature of the chromophore, i.e. if the semiconductor itself or the chemisorbed dye sensitizer, different energy levels will be involved in the cathodic ET process. An analysis of the general properties and requirements of electrodic materials of p type for being efficient photoelectrocatalysts of reduction processes in dye sensitized solar cells (DSC) will be given. The working principle of p type DSCs will be described and extended to other p type PECs conceived and developed for the conversion of the solar radiation into chemical products of energetic/chemical interest like non fossil fuels or derivatives of carbon dioxide.
author_names: Matteo Bonomo

Danilo Dini
title: Nanostructured p Type Semiconductor Electrodes and Photoelectrochemistry of Their Reduction Processes
year: 2016

abstract: Li4Ti5O12 is a promising anode material for rechargeable lithium batteries due to its well known zero strain and superb kinetic properties. However, Li4Ti5O12 shows low energy density above 1 V vs Li(/Li. In order to improve the energy density of Li4Ti5O12, its low voltage intercalation behavior beyond Li7Ti5O12 has been demonstrated. In this approach, the extended voltage window is accompanied by the decomposition of liquid electrolyte below 1 V, which would lead to an excessive formation of solid electrolyte interphase (SEI) films. We demonstrate an effective method to improve electrochemical performance of Li4Ti5O12 in a wide working voltage range by coating Li4Ti5O12 powder with p type semiconductor NiOx. Ex situ XRD, XPS, and FTIR results show that the NiOx coating suppresses electrochemical reduction reactions of the organic SEI components to Li2CO3, thereby promoting reversibility of the charge/discharge process. The NiOx coating layer offers a stable SEI film for enhanced rate capability and cyclability.
author_names: Mi Ru Jo

Gi-Hyeok Lee

Yong-Mook Kang
title: Controlling Solid Electrolyte Interphase Layer by Coating P Type Semiconductor NiOx on Li4Ti5O12 for High Energy Density Lithium Ion Batteries.
venue: ACS applied materials interfaces
year: 2015

abstract: Abstract This study adopted the sol gel method to synthesize p type semiconductor CuCrO 2 films and analyzed the effects of an annealing treatment, under a controlled argon atmosphere by changing the temperature and time, on the phase transformation, micro and nano structure, composition, and semiconductor properties of thin films. In the Cu Cr O phase transformation system, CuO, Cr 2 O 3 and CuCr 2 O 4 were the intermediate phases of the reaction for forming CuCrO 2 in the metastable state reaction process, the composite phases changed into a single phase, CuCrO 2 in the stable state reaction process of CuCrO 2 carbon elements of precursors were released and eliminated; and finally the optoelectronic properties of the CuCrO 2 thin film were adjusted and changed. The CuCrO 2 thin film possessed cell and polygon like shaped microstructures. The carbon content in the CuCrO 2 film decreased, so the copper, chromium, and oxygen contents increased accordingly. The optical band gap of CuCrO 2 thin film increased from 2.81 eV to 3.05 eV, while the resistivity decreased. The nanoscale crystal was identified which also of the delafossite CuCrO 2 structure. Using the sol gel method to prepare the CuCrO 2 thin films, an appropriate annealing temperature and time were helpful in forming the single phase CuCrO 2 the decrease of precursor elements in the thin film could enhance the band gap and the conductivity of the material.
author_names: Ruei-Sung Yu

De-He Hu
title: Formation and characterization of p type semiconductor CuCrO2 thin films prepared by a sol gel method
year: 2015

abstract: Achieving stable operation of photoanodes used as components of solar water splitting devices is critical to realizing the promise of this renewable energy technology. It is shown that p type transparent conducting oxides (p TCOs) can function both as a selective hole contact and corrosion protection layer for photoanodes used in light driven water oxidation. Using NiCo2O4 as the p TCO and n type Si as a prototypical light absorber, a rectifying heterojunction capable of light driven water oxidation was created. By placing the charge separating junction in the Si using a np( structure and by incorporating a highly active heterogeneous Ni Fe oxygen evolution catalyst, efficient light driven water oxidation can be achieved. In this structure, oxygen evolution under AM1.5G illumination occurs at 0.95 V vs RHE, and the current density at the reversible potential for water oxidation (1.23 V vs RHE) is >25 mA cm( 2) Stable operation was confirmed by observing a constant current density over 72 h and by sensitive measurements of corrosion products in the electrolyte. In situ Raman spectroscopy was employed to investigate structural transformation of NiCo2O4 during electrochemical oxidation. The interface between the light absorber and p TCO is crucial to produce selective hole conduction to the surface under illumination. For example, annealing to produce more crystalline NiCo2O4 produces only small changes in its hole conductivity, while a thicker SiOx layer is formed at the n Si/p NiCo2O4 interface, greatly reducing the PEC performance. The generality of the p TCO protection approach is demonstrated by multihour, stable, water oxidation with n InP/p NiCo2O4 heterojunction photoanodes.
author_names: Le Chen

Jinhui Yang

Shannon Klaus

Lyman J Lee

Rachel Woods-Robinson

Jie Ma

Yanwei Lum

Jason K Cooper

Francesca M Toma

Lin-wang Wang

Ian D Sharp

Alexis T Bell

Joel W Ager
title: p Type Transparent Conducting Oxide/n Type Semiconductor Heterojunctions for Efficient and Stable Solar Water Oxidation.
venue: Journal of the American Chemical Society
year: 2015

abstract: Abstract In this study, a H2S gas sensing element, hexagonal YMnO3 nanopowder, was prepared using a novel citrate method followed by calcination at different temperatures. Structural and microstructural characterizations were carried out using X ray diffraction (XRD) and transmission electron microscopy (TEM) respectively. XRD studies confirmed the formation of YMnO3 with a perovskite phase. The electrical properties were studied using impedance analysis; the results indicated that the conductivity depends on temperature. The presence of functional groups was determined using Fourier transform infrared spectroscopy (FT IR) Thermal stability was determined by thermogravimetric analysis (TG/DTA) Moreover, the pore size distribution measurements and scanning electron microscopy (SEM) images of the perovskite YMnO3 reveal the mesoporous characteristics of the material. Hexagonal YMnO3 nanopowder annealed at 700 degC was used in a chemoresistive gas sensing device. The response, selectivity, and sensitivity of the sensing material were measured by changing the electrical resistance of the material. The results demonstrated that the hexagonal YMnO3 nanopowder exhibited good sensing performance for hydrogen sulfide gas (H2S) with a rapid response and high sensitivity at 100 degC for 20 ppm. The cross sensitivity was also checked for reducing gases such as CO, H2, and LPG. The sensing mechanism of the YMnO3 sensor to H2S is also discussed.
author_names: Chandran Balamurugan

Dong-Weon Lee
title: Perovskite hexagonal YMnO3 nanopowder as p type semiconductor gas sensor for H2S detection
year: 2015

abstract: A practical strategy is proposed to facilitate the migration of holes in semiconductor (the low rate of which limits photocatalytic efficiency) by taking advantage of the Schottky barrier between p type semiconductor and metal. A high work function is found to serve as an important selection rule for building such desirable Schottky junction between semiconductor surface facets and metal. The intrinsic charge spatial distribution has to be taken into account when selecting the facets, as it results in accumulation of photoexcited electrons and holes on certain semiconductor facets. Importantly, the facets have a high work function, the same characteristic required for the formation of Schottky junction in a p type semiconductor metal hybrid structure. As a result, the semiconductor crystals in the hybrid design may be better enclosed by single facets with high work function, so as to synergize the two effects: Schottky barrier versus charge spatial separation.
author_names: Li-li Wang

Jing Ge

Ailun Wang

Mingsen Deng

Xijun Wang

Song Bai

Rui Li

Jun Jiang

Qun Zhang

Yi Luo

Yujie Xiong
title: Designing p type semiconductor metal hybrid structures for improved photocatalysis.
venue: Angewandte Chemie
year: 2014

abstract: Rhodium doped barium titanate (BaTiO3:Rh) powder was prepared by the polymerized complex (PC) method, and the photocatalytic activity for H2 evolution from water was examined. BaTiO3 is a wide gap n type semiconductor having a band gap of 3.0 eV. Doping Rh species into the lattice of BaTiO3 resulted in the formation of new absorption bands in visible light region. Upon visible light (l 420 nm) BaTiO3:Rh modified with nanoparticulate Pt as a water reduction promoter was capable of producing H2 from water containing an electron donor such as methanol and iodide. The best material prepared by the PC method exhibited higher activity than that made by a conventional solid state reaction method. Visible light driven Z scheme water splitting was also accomplished using Pt/BaTiO3:Rh as a building block for H2 evolution in combination with PtOx loaded WO3 as an O2 evolution photocatalyst in the presence of an IO3( /I( shuttle redox mediator. Photoelectrochemical analysis indicated that a porous BaTiO3:Rh electrode exhibited cathodic photoresponse due to water reduction in a neutral aqueous Na2SO4 solution upon visible light.
author_names: Kazuhiko Maeda
title: Rhodium doped barium titanate perovskite as a stable p type semiconductor photocatalyst for hydrogen evolution under visible light.
venue: ACS applied materials interfaces
year: 2014

abstract: The failure to develop a degenerate, wide band gap, p type oxide material has been a stumbling block for the optoelectronics industry for decades. Mg doped LaCuOSe has recently emerged as a very promising p type anode layer for optoelectronic devices, displaying high conductivities and low hole injection barriers. Despite these promising results, many questions regarding the defect chemistry of this system remain unanswered, namely (i) why does this degenerate semiconductor not display a Moss Burnstein shift? (ii) what is the origin of conductivity in doped and un doped samples? and (iii) why is Mg reported to be the best dopant, despite the large cation size mismatch between Mg and La? In this article we use screened hybrid density functional theory to study both intrinsic and extrinsic defects in LaCuOSe, and identify for the first time the source of charge carriers in this system. We successfully explain why LaCuOSe does not exhibit a Moss Burstein shift, and we identify the source of the subgap optical absorption reported in experiments. Lastly we demonstrate that Mg doping is not the most efficient mechanism for p type doping LaCuOSe, and propose an experimental reinvestigation of this system.
author_names: David O Scanlon

John Buckeridge

C Richard A Catlow

Graeme W Watson
title: Understanding doping anomalies in degenerate p type semiconductor LaCuOSe
year: 2014