高击穿电压的AIGaN/GaN FP-HEMT研究与分析

就蓝宝石衬底上制备的AlGaN／GaN场（field plate）HEMT器件、常规HEMT器件性能进行了分析对比．结果证明两种结构的器件直流参数变化不大，但是采用场板后器件的击穿电压从52V提高到了142V．在此基础上利用Sivaco软件对两种器件进行模拟仿真，深入分析了FP对器件击穿电压的影响．     

高击穿电压的AlGaN/GaN FP-HEMT研究与分析

就蓝宝石衬底上制备的AlGaN/GaN场板(field plate)HEMT器件、常规HEMT器件性能进行了分析对比.结果证明两种结构的器件直流参数变化不大，但是采用场板后器件的击穿电压从52V提高到了142V.在此基础上利用Sivaco软件对两种器件进行模拟仿真，深入分析了FP对器件击穿电压的影响.     

场板结构AlGaN/GaN HEMT的电流崩塌机理

在不同的漏偏压下，研究了钝化和不同场板尺寸AlGaN/GaN HEMT对电流崩塌的抑制能力.实验结果表明，钝化器件对电流崩塌的抑制能力随着漏偏压的升高而显著下降；在高漏偏压下，场板的尺寸对器件抑制崩塌的能力有较大影响，而合适尺寸的场板结构在各个漏偏压下都能够很好的抑制电流崩塌.深入分析发现，场板结构不仅能够抑制虚栅的充电过程，而且提供了放电途径，有利于虚栅的放电，从而抑制电流崩塌.在此基础上，通过建立场板介质对虚栅放电的模型，解释了高漏偏压下场板的尺寸对器件抑制崩塌的能力有较大影响的原因.     

壳聚糖-铜离子有序凝聚体的形貌

壳聚糖-铜离子有序凝聚体的形貌;形貌学;原子力显微镜     

Effect of annealing on performance of PEDOT:PSS/n-GaN Schottky solar cells

We develop a heterojunction-based Schottky solar cell consisting of n-type GaN and PEDOT：PSS and also investigate the effect of annealing on the performance of the solar cell. The results show that the open circuit voltage （Voc） increases from 0.54 V to 0.56 V, 0.71 V and 0.82 eV while decreases to 0.69 eV after annealing at 100 ℃, 130 ℃, 160 ℃, and 200 ℃, respectively, which can be ascribed to the change of barrier height of PEDOT：PSS/GaN Schottky contact induced by variation of the work function of the PEDOT：PSS. Furthermore, the conductivity and surface roughness measurements of the PEDOT：PSS indicate that annealing can increase the grain size and improve the connectivity between PEDOT and PSS particles, and cause thermal degradation at the same time, which leads to the rise in short-circuit current density （ISC） up to 160 ℃ and the dropoff in ISC after annealing at 200 ℃.     

Investigation of passivation effects in AlGaN/GaN metal-insulator-semiconductor high electron-mobility transistor by gate-drain conductance dispersion study

This paper studies the drain current collapse of AlGaN/GaN metal-insulator-semiconductor high electron-mobility transistors (MIS-HEMTs) with NbAlO dielectric by applying dual-pulsed stress to the gate and drain of the device.For NbAlO MIS-HEMT,smaller current collapse is found,especially when the gate static voltage is 8 V.Through a thorough study of the gate-drain conductance dispersion,it is found that the growth of NbAlO can reduce the trap density of the AlGaN surface.Therefore,fewer traps can be filled by gate electrons,and hence the depletion effect in the channel is suppressed effectively.It is proved that the NbAlO gate dielectric can not only decrease gate leakage current but also passivate the AlGaN surface effectively,and weaken the current collapse effect accordingly.     

SiC衬底上异质外延GaN薄膜XPS谱和PL谱研究

利用X射线光电子能谱,对在SiC衬底上采用MOCVD异质外延的未故意掺杂的GaN进行N、Ga组份测试,同时用光致发光技术对样品进行发光特性的研究.结果表明,随着GaN薄膜中Ga百分含量逐渐减小,室温下黄光输出峰值强度却逐渐增加.因此,在Ga含量相对低的GaN薄膜中容易形成Ga空位(即Ga空位浓度较高),而此时,黄光辐射强度单调递增证明,黄光辐射与VGa密切相关.     

Hybrid solar cell based on polythiophene and GaN nanoparticles composite

Hybrid solar cells based on poly(3-hexylthiophene)(P3HT)and Galium nitride(GaN)nanoparticle bulk heterojunction are fabricated and analyzed.The GaN nanocrystal is synthesized by means of a combination of sol–gel process with high temperature ammoniation using Ga(OC2H5)as a precursor.Their characteristics are determined by X-ray diffraction,X-ray photoelectron spectroscopy,and scanning electron microscopy.With the addition of GaN nanoparticle to P3HT,the device performance is greatly enhanced.     

场板结构AlGaN/GaN HEMT的电流崩塌机理

在不同的漏偏压下,研究了钝化和不同场板尺寸AlGaN/GaN HEMT对电流崩塌的抑制能力.实验结果表明,钝化器件对电流崩塌的抑制能力随着漏偏压的升高而显著下降;在高漏偏压下,场板的尺寸对器件抑制崩塌的能力有较大影响,而合适尺寸的场板结构在各个漏偏压下都能够很好的抑制电流崩塌.深入分析发现,场板结构不仅能够抑制虚栅的充电过程,而且提供了放电途径,有利于虚栅的放电,从而抑制电流崩塌.在此基础上,通过建立场板介质对虚栅放电的模型,解释了高漏偏压下场板的尺寸对器件抑制崩塌的能力有较大影响的原因. 关键词： AlGaN/GaN HEMT 场板 电流崩塌     

磁性多层膜磁特性的表面效应

利用Monte-Carlo方法和转移矩阵法研究了具有不同表面交换耦合J_s和薄膜厚度 磁性多层 膜的表面和尺寸对磁相变的影响.模拟结果表明，系统的相变温度随薄膜层数的变化取决于J_s/J(J为体内交换耦合)，当J_s/J大于某一临界值时，由于表面磁 有序先于体内磁有序 ，系统的相变温度随薄膜层数的增多而降低，反之，表面磁无序可与体内磁有序共存，系统 的相变温度随薄膜层数的增多而升高；当J_s/J较小时，随J_s增大 ，系统的居里温度缓慢 升高，趋近于体内相变温度，而当J_s/J较大时，随J_s增大，系统的 居里温度 呈线性升高.模拟结果与用转移矩阵法推导出的结果相当符合，且很好地解释了实验事实. 关键词： 磁星多层膜 交换耦合 Monte-Carlo模拟 转移矩阵法