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Ferromagnetism in Fe-doped CuO nanopowder

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Journal of Semiconductors 2012年第1期33卷 29-31页

作者： Zhao Jing Xia Qinglin li jinmin Semiconductor lighting Research and Development Center Institute of Semiconductors Chinese Academy of SciencesBeijing 100083China School of Physics and Electronics Central South University Changsha 410083China

The Fe-doped CuO nanopowder was synthesized by following the standard solid-state reaction method. The structure and magnetic properties of the Fe-doped CuO nanopowder were investigated. X-ray diffraction spec- tra confirmed the monoclinic structure of CuO and no secondary phase was detected, indicating that the Fe ions were incorporated into CuO. The ferromagnetism in Fe-doped CuO was studied and is believed to originate from the interaction between Fe ions and Cu ions via a super-exchange interaction or F-center mediated exchange interaction.

关键词： diluted magnetic semiconductors ferromagnetism Fe-doped CuO

Growth and Characterization of Semi-Insulating GaN Films Grown by MOCVD

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Journal of Rare Earths 2006年第Z1期24卷 14-18页

作者： Fang Cebao Wang Xiaoliang Hu Guoxin Wang Junxi Wang Cuimei li jinmin Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 China Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 China Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 China Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 China Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 China Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 China

High resistivity unintentionally doped GaN films were grown on (0001) sapphire substrates by metalorganic chemical vapor deposition. The surface morphology of the layer was measured by both atomic force microscopy and scanning electron microscopy. The results show that the films have mirror-like surface morphology with root mean square of 0.3 nm. The full width at half maximum of double crystal X-ray diffraction rocking curve for (0002) GaN is about 5.22 arcmin, indicative of high crystal quality. The resistivity of the GaN epilayers at room temperature and at 250 ℃ was measured to be approximate 109 and 106 Ω·cm respectively, by variable temperature Hall measurement. Deep level traps in the GaN epilayers were investigated by thermally stimulated current and resistivity measurements.

关键词： MOCVD GaN resistivity TSC

Exploration of photosensitive polyimide as the modification layer in thin film microcircuit

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Journal of Semiconductors 2018年第2期39卷 74-77页

作者： lily liu Changbin Song Bin Xue Jing li Junxi Wang jinmin li Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 China Beijing Engineering Research Center for the 3rd Generation Semiconductor Materials and Application Beijing 100083 China State Key Laboratory of Solid State lighting Chinese Academy of Sciences Beijing 100083 China Research and Development Center for Semiconductor lighting Chinese Academy of Sciences Beijing 100083 China

Positive type photosensitive polyimide is used as the modification layer in the thin film transistors production process. The photosensitive polyimide is not only used as the second insulating layer, it can also be used instead of a mask because of the photosensitivity. A suitable curing condition can help photosensitive polyimide form the high performance polyimide with orderly texture inside, and the performance of imidization depends on the precise control of temperature, time, and heat control during the curing process. Therefore, experiments of different stepped up heating tests are made, and the ability of protecting silicon dioxide is analyzed.

关键词： thin film microcircuit photosensitive polyimide silicon dioxide imidization temperature

Implementation of slow and smooth etching of GaN by inductively coupled plasma

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Journal of Semiconductors 2018年第11期39卷 19-24页

作者： Xilin li Ping Ma Xiaoli Ji Tongbo Wei Xiaoyu Tan Junxi Wang jinmin li Research and Development Center for Solid State lighting Institute of Semiconductors Chinese Academy of SciencesBeijing 100083 China University of Chinese Academy of Sciences Beijing 100049 China Beijing Engineer Research Center for the 3rd Generation Semiconductor Materials and Application Beijing 100083 China

Slow and smooth etching of gallium nitride（GaN） by BCl;/Cl;-based inductively coupled plasma（ICP）is investigated in this paper. The effects of etch parameters, including ICP power, radio frequency（RF） power, the flow rate of Cl;and BCl;, on GaN etch rate and etch surface roughness RMS are discussed. A new model is suggested to explain the impact mechanism of the BCl;flow rate on etch surface roughness. An optimized etch result of a slow and smooth etch surface was obtained; the etch rate and RMS were 0.36 ?/s and 0.9 nm, respectively.

关键词： GaN ICP slow etching smooth etching

The effect of AlN/AlGaN superlattices on crystal and optical properties of AlGaN epitaxial layers

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Journal of Semiconductors 2017年第11期38卷 22-25页

作者： Shuo Zhang Yun Zhang Xiang Chen Yanan Guo Jianchang Yan Junxi Wang jinmin li Research and Development Center for Solid State lighting Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 China University of Chinese Academy of Sciences Beijing 100049 China Beijing Engineering Research Center for the 3rd Generation Semiconductor Materials and Application Beijing 100083 China State Key Laboratory of Solid State lighting Beijing 100083 China

We investigate the effect of AlN/AlGaN superlattices（SLs） on crystal and optical properties of AlGN epitaxial layers. The result indicates that the crystal quality of AlGaN layers is consistent within a wide range of SLs thicknesses, while the optical properties are opposite. With SLs thickness decreasing from 20/44 to 17/36 and 15/29 nm, the full-width at half maximum of X-ray rocking curves for （0002）- and（1012）-plane of n-AlGaN layers grown on SLs are consistent of around 250 arcsec and 700 arcsec, respectively. Meanwhile, the center of the low optical transmittance band decreases from 326 to 279 nm and less than 266 nm as the SLs thickness decreases.280 nm deep ultraviolet light-emitting diodes（DUV-LEDs） structures are further regrown on the n-AlGaN *** electroluminescent intensities of samples are 30% higher than that of the sample whose low optical transmittance band appears around 279 nm. Optical simulations reveal that the SLs acts as distributed Bragg reflectors, thus less photons of the corresponding wavelength escape from the sapphire backside.

关键词： AlN AlGaN superlattices crystal quality transmittance light-emitting diodes

Performance improvement of light-emitting diodes with double superlattices confinement layer

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Journal of Semiconductors 2018年第11期39卷 47-50页

作者： Cheng Cheng Yan Lei Zhiqiang liu Miao He Zhi li Xiaoyan Yi Junxi Wang jinmin li Deping Xiong Center for Semiconductor lighting Chinese Academy of Sciences Beijing 100083 China University of Chinese Academy of Sciences Beijing 100049 China School of Physics and Optoelectronic Engineering Guangdong University of Technology Guangzhou 510006 China

In this study, the effect of double superlattices on GaN-based blue light-emitting diodes(LEDs) is analyzed numerically. One of the superlattices is composed of InGaN/GaN, which is designed before the multiple quantum wells(MQWs). The other one is AlinGaN/AlGaN, which is inserted between the last QB(quantum barriers) and p-GaN. The crucial characteristics of double superlattices LEDs structure, including the energy band diagrams, carrier concentrations in the active region, light output power, internal quantum efficiency, respectively,were analyzed in detail. The simulation results suggest that compared with the conventional AlGaN electronblocking layer(EBL) LED, the LED with double superlattices has better performance due to the enhancement of electron confinement and the increase of hole injection. The double superlattices can make it easier for the carriers tunneling to the MQWs, especially for the holes. Furthermore, the LED with the double superlattices can effectively suppress the electron overflow out of multiple quantum wells simultaneously. From the result, we argue that output power is enhanced dramatically, and the efficiency droop is substantially mitigated when the double superlattices are used.

关键词： double superlattices LED GaN

Fast and uniform growth of graphene glass using confined-flow chemical vapor deposition and its unique applications

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Nano Research 2016年第10期9卷 3048-3055页

作者： Zhaolong Chen Baolu Guan Xu-dong Chen Qing Zeng li lin Ruoyu Wang Manish Kr. Priydarshi Jingyu Sun Zhepeng Zhang Tongbo Wei jinmin li Yanfeng Zhang Yingying Zhang Zhongfan liu Center for Nanochemistry (CNC) Beijing Science and Engineering Center for Nanocarbons College of Chemistry and Molecular Engineering Peking University Beijing 100871 China Key Laboratory of Opto-electronics Technology Ministry of Education Beijing University of Technology Beijing 100124 China ing 100083 China Department of Materials Science and Engineering College of Engineering Peking University Beijing 100871 China Department of Chemistry and Center for Nano and Micro Mechanics Tsinghua University Beijing 100084 China

Fast and uniform growth of high-quality graphene on conventional glass is of great importance for practical applications of graphene glass. We report herein a confined-flow chemical vapor deposition （CVD） approach for the high- efficiency fabrication of graphene glass. The key feature of our approach is the fabrication of a 2-4 μm wide gap above the glass substrate, with plenty of stumbling blocks; this gap was found to significantly increase the collision probability of the carbon precursors and reactive fragments between one another and with the glass surface. As a result, the growth rate of graphene glass increased remarkably, together with an improvement in the growth quality and uniformity as compared to those in the conventional gas flow CVD technique. These high-quality graphene glasses exhibited an excellent defogging performance with much higher defogging speed and higher stability compared to those previously reported. The graphene sapphire glass was found to be an ideal substrate for growing uniform and ultra-smooth aluminum nitride thin films without the tedious pre-deposition of a buffer layer. The presented confined- flow CVD approach offers a simple and low-cost route for the mass production of graphene glass, which is believed to promote the practical applications of various graphene glasses.

关键词： graphene glass confined-flow chemicalvapor deposition transparent heating device epitaxial A1N film

Growth and characterization of 0.8-μm gate length AlGaN/GaN HEMTs on sapphire substrates

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Science in China(Series F) 2005年第6期48卷 808-814页

作者： WANG Xiaoliang WANG Cuimei HU Guoxin WANG Junxi RAN Junxue FANG Cebao li Jianping ZENG Yiping li jinmin liU Xinyu liU Jian QIAN He Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 China Institute of Microelectronics Chinese Academy of sciences Beijing 100029 China

AIGaN/GaN high electron mobility transistor （HEMT） structures were grown on 2 inch sapphire substrates by MOCVD, and 0.8-μm gate length devices were fabricated and measured. It is shown by resistance mapping that the HEMT structures have an average sheet resistance of approximately 380 Ω/sq with a uniformity of more than 96%. The 1-mm gate width devices using the materials yielded a pulsed drain current of 784 mA/mm at Vgs=0.5 V and Vds=7 V with an extrinsic transconductance of 200 mS/mm. A 20-GHz unity current gain cutoff frequency （fT） and a 28-GHz maximum oscillation frequency （fmax） were obtained. The device with a 0.6-mm gate width yielded a total output power of 2.0 W/mm （power density of 3.33 W/mm） with 41% power added efficiency （PAE） at 4 GHz.

关键词： HEMT GaN MOCVD power device

Study on Surface Morphology of GaN Growth by MOCVD on GaN/Si(111)Template

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Journal of Rare Earths 2006年第Z1期24卷 11-13页

作者： liu Zhe Wang Junxi Wang Xiaoliang Hu Guoxin Guo Lunchun liu Hongxin li Jianping li jinmin Zeng Yiping Novel Materials Laboratory Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China

The surface morphology of GaN grown by MOCVD on GaN/Si template was *** morphology and deep pinhole defects on some surface areas of the samples were observed and *** formation of rough morphology is possibly related to Ga-Si alloy produced due to poor thermal stability of template at high *** deep pinhole defects generated are deep down to the surface of MBE-grown GaN/Si *** stress originated from the large thermal expansion coefficient difference between GaN and Si may be related to the formation of the pinhole *** surface morphology of the GaN can be improved by optimizing the GaN/Si template and decreasing the growth temperature.

关键词： surface morphology GaN/Si template GaN MOCVD