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Improved electrical properties of the two-dimensional electron gas in AlGaN/GaN heterostructures using high temperature AlN interlayers

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Science China(Technological Sciences) 2010年第6期53卷 1567-1571页

作者： XUE JunShuai,HAO Yue,ZHANG JinCheng & NI JinYu Key Laboratory of Wide Band-Gap semiconductors and Devices,School of Microelectronics,xidian University,xi’an 710071,China Key Laboratory of Wide Band-Gap semiconductors and Devices School of Microelectronics Xidian University

The electrical properties of two-dimensional electron gas (2DEG) in AlGaN/GaN heterostructures using high temperature (HT) AlN interlayers (ITs) grown on c-plane sapphire substrate by metal organic chemical vapor deposition (MOCVD) have been *** is found that the electrical properties (electron mobility and sheet carrier density) are improved compared with those in the conventional AlGaN/GaN heterostructures without HT AlN ITs,and the improved 2DEG properties result in the reduction of the sheet *** results from high resolution X-ray diffraction (HRXRD) and Raman spectroscopy measurements show that HT AlN ITs increase the in-plane compressive strain in the upper GaN layer,which enhances the piezoelectric polarization in it and consequently causes increasing of 2DEG density at the AlGaN/GaN ***,the compressive strain induced by HT AlN ITs leads to a less tensile strain in AlGaN barrier layer and causes positive and negative effects on the sheet carrier density of 2DEG,which counteract each *** HT AlN ITs reduce the lattice mismatch between the GaN and AlGaN layers and smooth the interface between them,thus increasing the electric mobility of 2DEG by weakening the alloy-related interface roughness and *** addition,the surface morphology of AlGaN/GaN heterostructures is improved by the insertion of HT AlN *** reason for the improved properties is discussed in this paper.

关键词： AlGaN/GaN heterostructures electrical properties two dimensional electron gas

A single-event-hardened phase-locked loop using the radiation-hardened-by-design technique

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Journal of semiconductors 2012年第10期33卷 97-102页

作者：韩本光郭仲杰吴龙胜刘佑宝 xi'an Microelectronic Technology Institute

A radiation-hardened-by-design phase-locked loop（PLL） with a frequency range of 200 to 1000 MHz is *** presenting a novel charge compensation circuit,composed by a lock detector circuit,two operational amplifiers,and four MOS devices,the proposed PLL significantly reduces the recovery time after the presence of a single event transient（SET）.Comparing with many traditional hardened methods,most of which endeavor to enhance the immunity of the charge pump output node to an SET,the novel PLL can also decrease its susceptibility in the presence of an SET in other blocks.A novel system model is presented to describe immunity of a PLL to an SET and used to compare the sensitivity of traditional and hardened PLLs to an *** SET is simulated on Sentaurus TCAD simulation workbench to model the induced pulse *** simulation with a 130 nm CMOS process model shows that the recovery time of the proposed PLL reduces by up to 93.5%compared with the traditional one,at the same time,the charge compensation circuit adds no complexity to the systemic parameter design.

关键词： phase-locked-loop single event effect SET hardened by design charge compensation

Photoelectric characteristics of an inverse U-shape buried doping design for crosstalk suppression in pinned photodiodes

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Journal of semiconductors 2014年第11期35卷 81-89页

作者：曹琛张冰李炘吴龙胜王俊峰 xi'an Microelectronics Technology Institute

A design of an inverse U-shape buried doping in a pinned photodiode （PPD） of CMOS image sensors is proposed for electrical crosstalk suppression between adjacent pixels. The architecture achieves no extra fill factor consumption, and proper built-in electric fields can be established according to the doping gradient created by the injections of the extremely low P-type doping buried regions in the epitaxial layer, causing the excess electrons to easily drift back to the photosensitive area rarely with a diffusion probability; the overall junction capacitance and photosensitive area extensions for a full well capacity （FWC） and internal quantum efficiency （IQE） improving are achieved by the injection of a buried N-type doping. By considering the image lag issue, the process parameters of all the injections have been precisely optimized. Optical simulation results based on the finite difference time domain method show that compared to the conventional PPD, the electrical crosstalk rate of the proposed architecture can be decreased by 60%-80% at an incident wavelength beyond 450 nm, IQE can be clearly improved at an incident wavelength between 400 and 600 nm, and the FWC can be enhanced by 107.5%. Furthermore, the image lag performance is sustained to a perfect low level. The present study provides important guidance on the design of ultra high resolution image sensors.

关键词： CMOS image sensor electrical crosstalk photoelectric performance design pinned photodiode

Pinch-off voltage modeling for CMOS image pixels with a pinned photodiode structure

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Journal of semiconductors 2014年第7期35卷 90-96页

作者：曹琛张冰吴龙胜李炘王俊峰 xi’an Microelectronics Technology Institute

A novel analytical model of pinch-off voltage for CMOS image pixels with a pinned photodiode structure is proposed. The derived model takes account of the gradient doping distributions in the N buried layer due to the impurity compensation formed by manufacturing processes; the impurity distribution characteristics of two boundary PN junctions located in the region for particular spectrum response of a pinned photodiode are quantitative analyzed. By solving Poisson＇s equation in vertical barrier regions, the relationships between the pinch-off voltage and the corresponding process parameters such as peak doping concentration, N type width and doping concentration gradient of the N buried layer are established. Test results have shown that the derived model features the variations of the pinch-off voltage versus the process implant conditions more accurately than the traditional model. The research conclusions in this paper provide theoretical evidence for evaluating the pinch-off voltage design.

关键词： pinned photodiode pixel design pinch-off voltage analytical model

Negative Bias Temperature Instability ＂Recovery＂ under Negative Stress Voltage with Different Oxide Thicknesses

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Chinese Physics Letters 2011年第1期28卷 175-178页

作者： CAO Yan-Rong MA xiao-Hua HAO Yue ZHU Min-Bo TIAN Wen-Chao ZHANG Yue School of Electronical and Machanical Engineering Xidian University Xi'an 710071 School of Technical Physics Xidian University Xi 'an 710071 Key Lab of Wide Band-Gap Semiconductor Materials and Devices Xi'an 710071

Different phenomena are observed under negative gate voltage stress which is smaller than the previous degra- dation stress in PMOSFETs with different oxide thicknesses. We adopt the real time method to make a point of the drain current to study the degradation and recovery of negative bias temperature instability （NBTI）. For the device with thin oxide, recovery phenomenon appears when smaller negative voltage stress was applied, due to the more influencing oxide charges detrapping effects than the interface states. For the device with thick oxide, not recovery but degradation phenomenon comes forth. As many charges are trapped in the deeper position and higher energy level in the oxide, these charges can not be detrapped. Therefore, the effect of the charge detrapping is smaller than that of the interface states in the thick oxide. The degradation presents itself during the ＇recovery＇ time.

关键词： Electronics and devices semiconductors

Flammable gases produced by TiO_(2) nanoparticles under magnetic stirring in water

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Friction 2022年第7期10卷 1127-1133页

作者： Pengcheng LI Chongyang TANG xiangheng xiAO Yanmin JIA Wanping CHEN School of Physics and Technology Wuhan UniversityWuhan 430072China School of Science Xi'an University of Posts and TelecommunicationsXi'an 710054China

The friction between nanomaterials and Teflon magnetic stirring rods has recently drawn much attention for its role in dye degradation by magnetic stirring in *** the friction between TiO_(2) nanoparticles and magnetic stirring rods in water has been deliberately enhanced and *** much as 1.00 g TiO_(2) nanoparticles were dispersed in 50 mL water in 100 mL quartz glass reactor,which got gas-closed with about 50 mL air and a Teflon magnetic stirring rod in *** suspension in the reactor was magnetically stirred in *** gases of 22.00 ppm CO,2.45 ppm CH_(4),and 0.75 ppm H_(2) were surprisingly observed after 50 h of magnetic *** reference,only 1.78 ppm CO,2.17 ppm CH_(4),and 0.33 ppm H_(2) were obtained after the same time of magnetic stirring without TiO_(2) *** magnetic stirring rods were simultaneously employed to further enhance the stirring,and as much as 30.04 ppm CO,2.61 ppm CH_(4),and 8.98 ppm H_(2) were produced after 50 h of magnetic stirring.A mechanism for the catalytic role of TiO_(2) nanoparticles in producing the flammable gases is established,in which mechanical energy is absorbed through friction by TiO_(2) nanoparticles and converted into chemical energy for the reduction of CO_(2) and H_(2)*** finding clearly demonstrates a great potential for nanostructured semiconductors to utilize mechanical energy through friction for the production of flammable gases.

关键词： friction magnetic stirring catalysis CO_(2)reduction TiO_(2)

Measurement of charge transfer potential barrier in pinned photodiode CMOS image sensors

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Journal of semiconductors 2016年第5期37卷 56-60页

作者：曹琛张冰王俊峰吴龙胜 xi'an Microelectronics Technology Institute xi’anMicroelectronicsTechnologyInstitute

The charge transfer potential barrier （CTPB） formed beneath the transfer gate causes a noticeable image lag issue in pinned photodiode （PPD） CMOS image sensors （CIS）, and is difficult to measure straightforwardly since it is embedded inside the device. From an understanding of the CTPB formation mechanism, we report on an alternative method to feasibly measure the CTPB height by performing a linear extrapolation coupled with a horizontal left-shift on the sensor photoresponse curve under the steady-state illumination. The theoretical study was pertbrmed in detail on the principle of the proposed method. Application of the measurements oil a prototype PPD-CIS chip with an array of 160 ×160 pixels is demonstrated. Such a method intends to shine new light oil the guidance for the lag-free and high-speed sensors optimization based on PPD devices.

关键词： CMOS image sensors (C1S) pinned photodiode (PPD) charge transfer potential barrier (CTPB) photoresponse curve

Two-dimensional electron gas characteristics of InP-based high electron mobility transistor terahertz detector

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Chinese Physics B 2018年第4期27卷 363-368页

作者： Jin-Lun Li Shao-Hui Cui Jian-xing Xu xiao-Ran Cui Chun-Yan Guo Ben Ma Hai-Qiao Ni Zhi-Chuan Niu Department of Missile Engineering Shijiazhuang Campus Army Engineering University Shijiazhuang 050003 China State Key Laboratory for Superlattices Institute of Semiconductors Chinese Academy of Sciences （CAS） Beijing 100083 China College of Materials Science and Opto-Electronic Technology University of Chinese Academy of Sciences Beijing 100049 China Microsystem ＆ Terahertz Research Center China Academy of Engineering Physics Chengdu 610200 China Wide Bandgap Semiconductor Technology Disciplines State Key Laboratory Xidian University Xi＇an 710071 China Key Laboratory of Ultra-fast Photoelectric Diagnostics Technology of Chinese Academy of Sciences Xi＇ an Institute of Optics and Precision Mechanics Xi＇ an 710119 China

The samples of InxGa（1-x）As/In（0.52）Al（0.48）As two-dimensional electron gas（2DEG）are grown by molecular beam epitaxy（MBE）.In the sample preparation process,the In content and spacer layer thickness are changed and two kinds of methods,i.e.,contrast body doping andδ-doping are *** samples are analyzed by the Hall measurements at 300 Kand 77 *** InxGa1-xAs/In0.52Al0.48As 2DEG channel structures with mobilities as high as 10289 cm^2/V·s（300 K）and42040 cm^2/V·s（77 K）are obtained,and the values of carrier concentration（Nc）are 3.465×10^12/cm^2 and 2.502×10^12/cm^2,*** THz response rates of In P-based high electron mobility transistor（HEMT）structures with different gate lengths at 300 K and 77 K temperatures are calculated based on the shallow water wave instability *** results provide a reference for the research and preparation of In P-based HEMT THz detectors.

关键词： THz detector high electron mobility transistor two-dimensional electron gas InP

Recent progress in synthesis of two-dimensional hexagonal boron nitride

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Journal of semiconductors 2017年第3期38卷 11-24页

作者： Haolin Wang Yajuan Zhao Yong xie xiaohua Ma xingwang Zhang School of Advanced Materials and Nanotechnology Xidian University Xi'an 710126 ＆ Key Laboratory of Wide Band-Gap Semiconductor Technology Xidian University Xi＇an 710071 China Key Lab of Semiconductor Materials Science Institute of Semiconductors CAS Beijing 100083 ＆ College of Materials Science and Opto-Electronic Technology University of Chinese Academy of Sciences Beijing 100049 China School of Materials Science and Engineering Shaanxi University of Science and Technology Xi＇an 710021 China

Two-dimensional（2D） materials have recently received a great deal of attention due to their unique structures and fascinating properties,as well as their potential applications.2D hexagonal boron nitride（2D hBN）,an insulator with excellent thermal stability,chemical inertness,and unique electronic and optical properties,and a band gap of 5.97 e V,is considered to be an ideal candidate for integration with other 2D ***,the controllable growth of high-quality 2D h-BN is still a great challenge.A comprehensive overview of the progress that has been made in the synthesis of 2D h-BN is presented,highlighting the advantages and disadvantages of various synthesis *** addition,the electronic,optical,thermal,and mechanical properties,heterostructures,and related applications of 2D h-BN are discussed.

关键词： hexagonal boron nitride two-dimensional materials applications synthesis