GaN中杂质和缺陷的特性

主要描述了ＧａＮ中施主和受主杂质的能级，氢在掺杂中的作用以及空位的某些特性，同时讨论了该领域未来的研究趋向。     

GaN材料的特性与应用

本介绍了GaN材料的特性、生长及应用，并展望了其应用前景。     

GaN材料系列的研究进展

ＧａＮ及其合金作为第三代半导体材料具有一系列优异的物理和化学性质，在光电子器件，高温大功率电子器件及高频微波器件应用方面具有广阔的前景，已成为当前高科技领域的研究重点，论述了这种材料的研究历史与发展现状，物理与化学性质，薄膜的生长方法及在光学电子和微电子器件应用于方面的研究进展。     

等电子杂质Sb对InP中缺陷的影响

用光致发光和正电子湮没技术研究了掺Sb InP单晶的“本征缺陷”。发现元素Sb的掺入导致磷空位(V_p)或者是V_p与杂质络合物的光致发光峰消失。用正电子湮没技术的测量也表明掺Sb的InP晶体中单空位浓度有所降低,两种方法测量的结果对应得很好。我们认为InP中掺Sb能有效地降低晶体中的本征缺陷。     

GaN的MOCVD生长

ＧａＮ是重要的蓝光半导体材料．我们以ＴＭＧａ和ＮＨ３为源在（０１１２）α－Ａｌ２Ｏ３衬底上成功的用ＭＯＣＶＤ方法生长了ＧａＮ外延层，研究了ＧａＮ的表面形貌与结晶学、电学和光学特性．ＧａＮ（２１１０）面的双晶回摆曲线衍射峰的最小半高宽已达１６＇．并观测到ＧａＮ所发出的紫外和可见光波段的阴极荧光．     

GaN薄膜技术的几点突破

简单回顾了半导体短波长激光器的发展过程,归纳了ＧａＮ基ＬＤ（激光器）制作中ＧａＮ膜的几点技术突破。     

GaN薄膜表面缺陷密度的提取

在GaN薄膜制备中，薄膜表面缺陷密度提取是改进质量的重要依据。文章通过对若干幅GaN薄膜缺陷图像的分析．提出一种GaN薄膜缺陷密度的提取方法。该方法首先果用闯值分割法二值化背影复杂的GaN薄膜表面图像：然后基于数学形态学方法提取出薄膜表面缺陷的密度；最后给出了薄膜表面缺陷粒径的分布模型。实验结果表明此方法使GaN薄膜表面缺陷提取简单且易于测量，为分析缺陷原因提高薄膜质量起到重要的指导作用。     

Defects in GaN Nanowires

High‐resolution transmission electron microscopy (HRTEM) and cross‐sectional transmission electron microscopy (XTEM) are used to characterize common defects in wurtzite GaN nanowires grown via a vapor–liquid–solid (VLS) mechanism. HRTEM shows that these nanowires contain numerous (001) stacking defects interspersed with small cubic GaN regions. Using XTEM, bicrystalline nanowires are discovered with twofold rotational twin axes along their growth directions, and are found to grow along high‐index directions or vicinal to low‐index planes. We propose a defect‐mediated VLS growth model to qualitatively account for the prevalence of these extended defects, and discuss the implications of these defects for nanowire growth kinetics and device behavior.     

Biphasic GaN nanowires: Growth mechanism and properties

Catalyst-free vapor-solid nanowire growth has been used to produce novel multiphase zinc-blende/wurtzite gallium nitride nanowires. Multiphase nanowire growth occurred at nanoscale nucleation sites on platelets of gallium nitride. Growth temperature has been shown to exert a strong influence on nucleation site formation. Scanning electron microscopy (SEM) was used to characterize the matrix from which the nanowires grew. Nanowires were characterized with transmission electron microscopy (TEM).     

SiNx 掩膜对GaN 外延薄膜性质的影响

研究了纳米量级的多孔 SiNx 插入层的生长位置对高质量GaN外延薄膜性质的影响。测量结果表明：当把SiNx 插入层生长在GaN 粗糙层上,能够得到最好的晶体质量;SiNx 插入层的生长位置对GaN 薄膜的应变大小基本没有影响;然而,插入层的位置改变了薄膜中的本征载流子浓度。     

Synthesis of GaN nanowires and nanorods via self-growth mode control

The synthesis of hexagonal wurzite one-dimensional (1D) GaN nanostructures on c-Al₂O₃ substrates was investigated using a thermal chemical vapor deposition (CVD) process. The diameter of the GaN nanostructures was controlled by varying the growth time using a mixture of GaN powder and Ga metal with the ammonia gas reaction. The morphologies of the GaN nanowires and nanorods were confirmed by field emission scanning electron microscopy. The micro-Raman spectroscopy and X-ray scattering measurements indicated that the GaN nanostructures had a hexagonal wurzite structure without any oxide phases. We investigated the difference in the structural properties between the GaN nanowires and nanorods. Deep-level emission bands were not observed in cathodoluminescence measurements from either the GaN nanowires or nanorods, indicating the incorporation of low-level impurities into our 1D GaN nanostructures.     

GaN上的欧姆接触

主要描述了在ｎ 型和ｐ 型ＧａＮ上制备欧姆接触的方法,分析了欧姆接触的特性及其形成机理, 并讨论了该领域未来的研究趋势     

Optical Properties of Nanocrystalline GaN Films Prepared by Annealing Amorphous GaN in Ammonia

Nanocrystalline GaN films were prepared by thermal treatment of amorphous GaN films under flowing NH₃ at a temperature of 600°C to 950°C for 1 h to 2 h. X-ray diffraction and field-emission scanning electron microscopy confirmed the formation of high-crystal-quality hexagonal GaN films with preferential (002) orientation. The photoluminescence spectrum showed a sharp peak near the band gap emission located at 368 nm and a broad blue peak centered at 430 nm. Five first-order Raman modes near ∼143 cm⁻¹, 535 cm⁻¹, 555 cm⁻¹, 568 cm⁻¹, and 731 cm⁻¹ with two new additional Raman peaks at 257 cm⁻¹ and 423 cm⁻¹ were observed. The origin of these new Raman peaks is discussed briefly.     

Investigation of three-step epilayer growth approach of GaN films to minimize compensation

The heteroepitaxial growth of gallium nitride (GaN) films using three distinct growth steps is investigated in terms of improving the electrical properties of the layer. The first step involves the deposition of a fixed quality aluminum nitride (AlN) layer on an a-plane sapphire substrate. The second step is aimed at maximizing the GaN grain size initially grown on the AlN. The third step is aimed at optimizing the surface morphology of the GaN layer. The means of transitioning the growth between steps is investigated and an optimum transition method is reported. Growth parameters investigated include pressure, trimethylgallium molar flow rate, and ratio of group V to group III precursor molar flows. Carrier statistics show a lower level of compensation in films grown at a slower growth rate in the second step and a moderate rate in the third step.     

A study of temperature field in a GaN heterostructure field-effect transistor

This paper presents a three-dimensional finite element based heat transfer model for a Gallium Nitride-based Heterostructure Field-Effect Transistor (henceforth referred to as GaN HFET). Analyses were carried out to study the distribution of temperature in the HFET under steady-state conditions for two different steady-current inputs. Two different substrates for the HFET, sapphire and silicon carbide (SiC), were studied. The paper discusses the effect of using a heat sink and also that of using reasonable contact resistances on the substrate side of the HFET, on the temperature profile. In all cases, the gate region of the HFET was found to attain the highest temperature. Subsequent experiments to validate the results of the computational analysis were carried out at the Oakridge National Laboratories, Knoxville, and are also presented in this paper.     

BESOI薄膜的缺陷分析和应力研究

用机械减薄和氧化剥层法获得表层硅厚度约０．４μｍ的ＢＥＳＯＩ薄膜。对这种薄膜用Ｓｅｃｃｏ腐蚀液腐蚀并分析了缺陷种类，计量了缺陷密度。用波长为０．５１４５μｍ的激光Ｒａｍａｎ谱测量了ＢＥＳＯＩ薄膜和界面附近的应力密度。结果表明，该薄膜的主要缺陷为氧化层错，密度约１．８×１０３／ｃｍ２，总的缺陷密度为２．６×１０３／ｃｍ２，张应力密度δ≤５×１０３Ｎ／ｃｍ２。