原子氢辅助分子束外延生长台阶状表面形貌的研究

研究了分子束外延中引入原子氢后,原子氢对外延层表面形貌特征形成的诱导作用.原子力显微镜(AFM)测试表明,在(311)A GaAs表面,原子氢导致了台阶状形貌的形成,在这种台阶状表面进一步生长了InAs量子点,测试结果表明其位置分布的有序化受到台阶高度和台阶周期的制约.这为实现量子点结构的有序化控制生长提供了一定的实验参考.     

原子氢辅助分子束外延生长台阶状表面形貌的研究

研究了分子束外延中引入原子氢后 ,原子氢对外延层表面形貌特征形成的诱导作用 .原子力显微镜 (AFM)测试表明 ,在 (311) A Ga As表面 ,原子氢导致了台阶状形貌的形成 ,在这种台阶状表面进一步生长了 In As量子点 ,测试结果表明其位置分布的有序化受到台阶高度和台阶周期的制约 .这为实现量子点结构的有序化控制生长提供了一定的实验参考 .     

InGaAs/InP材料的MOCVD生长研究

研究了InGaAs/InP材料的MOCVD生长技术和材料的性能特征。InP衬底的晶向偏角能够明显影响外延生长模型以及外延层的表面形貌,用原子力显微镜(AFM)观察到了外延层表面原子台阶的聚集现象(step-bunching现象),通过晶体表面的原子台阶密度和二维生长模型解释了台阶聚集现象的形成。对外延材料进行化学腐蚀,通过双晶X射线衍射(DCXRD)分析发现异质结界面存在应力,用异质结界面岛状InAs富集解释了应力的产生。通过严格控制InGaAs材料的晶格匹配,并优化MOCVD外延生长工艺,制备出厚层InGaAs外延材料,获得了低于1×1015cm-3的背景载流子浓度和良好的晶体质量。     

GaAs（331）A衬底上分子束外延生长自组织InAs纳米结构形貌演化机制

采用分子束外延方法在GaAs(331)A高指数衬底上制备自对齐InAs量子线(QWR)或者三维(3D)岛状结构。InAs量子线(QWR)选择性生长在GaAs层的台阶边缘。通过原子力显微镜(AFM)仔细研究了InAs纳米微结构的表面形貌，发现不同的生长条件如衬底温度、生长速率和InAs层厚度等，对InAs表面形貌有很大的影响。低温更容易导致线状纳米微结构的形成，而高温更利于3D岛状结构形成。表面形貌的转变归结于表面能同应变能之间的竞争。     

氢在GaAs(110)表面吸附的研究

采用EHMO方法计算了氢在GaAs(110)表面的吸附,确定了氢原子在表面的吸附位置.计算结果表明,Ga与As都能吸附氢原子,最稳定的吸附位置在As的悬键位,其次为Ga的悬键位;氢与表面原子形成共价键,键长均约为1.32A|°.当氢原子吸附于As的悬键位时,禁带中出现由As原子及Ga原子引入的表面态.同时计算表明GaAs(110)表面不能吸附分子态的氢,与已知的实验结果相符.     

偏晶向(0001)Si-面衬底上4H-SiC的LPCVD外延生长

化学气相沉积(CVD)是微电子器件用SiC外延材料的主要生长技术.为了获得高质量的4H-SiC外延材料,在偏向<1120>方向8°的4H-SiC(0001)Si-面衬底上,利用台阶控制生长技术进行4H-SiC的同质外延生长.表面形貌是SiC外延材料质量好坏的一个重要参数,为此研究了表面形貌与工艺参数的关系,探讨了4H-SiC外延膜的表面缺陷形成原因.利用Raman散射技术研究了非均匀4H-SiC外延材料的多晶型现象.     

偏晶向(0001)Si-面衬底上4H-SiC的LPCVD外延生长

化学气相沉积(CVD)是微电子器件用SiC外延材料的主要生长技术.为了获得高质量的4H-SiC外延材料,在偏向<1120>方向8°的4H-SiC(0001)Si-面衬底上,利用台阶控制生长技术进行4H-SiC的同质外延生长.表面形貌是SiC外延材料质量好坏的一个重要参数,为此研究了表面形貌与工艺参数的关系,探讨了4H-SiC外延膜的表面缺陷形成原因.利用Raman散射技术研究了非均匀4H-SiC外延材料的多晶型现象.     

两步生长和直接生长GaAs/Si单晶薄膜的比较

报道了采用热壁外延(HWE)技术,在(100),(111)和(211)三种典型Si表面通过两步生长和直接生长法制备GaAs单晶薄膜,经过拉曼光谱、霍尔测试和荧光光谱分析比较,得出结论:(1)相同取向Si衬底,两步生长法制备的GaAs薄膜结晶质量比直接生长法制备的GaAs薄膜的要好;(2)采用HWE技术在Si上异质外延GaAs薄膜,其表面缓冲层的生长是降低位错、提高外延质量的基础;(3)不同取向Si衬底对GaAs外延层结晶质量有影响, (211)面外延的GaAs薄膜质量最好,(100)面次之,(111)面最差.     

偏晶向(0001)Si-面衬底上4H-SiC的LPCVD外延生长

化学气相沉积（CVD）是微电子器件用SiC外延材料的主要生长技术. 为了获得高质量的4H-SiC外延材料，在偏向〈1120〉方向8. 的4H-SiC (0001) Si-面衬底上，利用台阶控制生长技术进行4H-SiC的同质外延生长. 表面形貌是SiC外延材料质量好坏的一个重要参数，为此研究了表面形貌与工艺参数的关系，探讨了4H-SiC外延膜的表面缺陷形成原因. 利用Raman散射技术研究了非均匀4H-SiC外延材料的多晶型现象.     

Si表面制备GaAs单晶薄膜的反相畴消除

极性半导体GaAs在非极性半导体Si表面外延生长,普遍选用(100)面Si材料作衬底,外延时由于Ga,As原子占据不合适的晶格位置,通常导致结构缺陷--反相畴产生,而选用(100)面偏向[011]方向4°或(211)面的Si作衬底,可以有效消除反相畴.     

Impurity incorporation and the surface morphology of MOVPE grown GaAs

The impact of impurity incorporation on the development of the surface morphology of GaAs epilayers, grown by metalorganic vapor phase epitaxy (MOVPE), has been systematically investigated. A variety of different doping elements, including Mg, Zn, C, Si, O, and Se, were used to study the interaction between the impurity atoms and GaAs surface. Impurity atoms with smaller atomic weight, belonging to group II and VI, have a larger influence on the surface morphology than the other dopants. Different chemical sources for carbon doping were also used to explore the effect of surface growth chemistry on the formation of surface features. The epilayer surface morphology was affected by the combination of several physical and chemical factors. Factorsinfluencing the impact of an impurity on the growth front evolution are presented based on the interaction between the impurity atoms and the surface step structures.     

Effect of hydrogen on the properties of Pd/GaAs/InGaAs diode structures with quantum wells

The effect of hydrogen on photoelectric properties and photoluminescence of Pd/GaAs/InGaAs diode structures with quantum wells (QWs) was investigated. The dependence of the structure characteristics on the thickness of the GaAs anodic oxide layer is revealed, and the optimum oxide thickness for the fabrication of hydrogen sensors is determined. It is established that the existence of metal bridges in a thin oxide layer has a significant influence on the I-V curves of the structures. It is shown that the presence of QWs leads to an increase in the structure’s sensitivity to hydrogen. Using the QWs as local defect probes, formation of the defects resulting from the deposition of a Pd electrode both on natural and on anodized GaAs surface is studied. It is found that defects in the QWs of the diode structures can be passivated by introduction of atomic hydrogen through the Pd electrode upon exposure of the structures to an atmosphere of molecular hydrogen.     

掺碳GaAs生长特性的研究

采用以碳纤维为碳源的固态源MBE技术，生长了不同厚度的重接碳GaAs以及具有不同表层厚度的δ碳掺杂GaAs，通过Nomarski干涉显微镜和原子力显微镜（AFM）对样品表面形貌的观察，分析了挨碳GaAs的生长过程和各种缺陷的产生，提出碳的掺入导致了GaAs材料的三维岛状生长，促进了各种缺陷的力生。提出了通过改善生长条件减少缺陷的途径。     

Growth features and spectroscopic structure investigations of nanoprofiled AlN films formed on misoriented GaAs substrates

Nanostructured aluminum-nitride films are formed by reactive ion-plasma sputtering onto GaAs substrates with different orientations. The properties of the films are studied via structural analysis, atomic force microscopy, and infrared and visible–ultraviolet spectroscopy. The aluminum-nitride films can have a refractive index in the range of 1.6–4.0 at a wavelength of ~250 nm and an optical band gap of ~5 eV. It is shown that the morphology, surface composition, and optical characteristics of AlN/GaAs heterophase systems can be controlled using misoriented GaAs substrates.     

Passivation of GaAs surfaces*

Exposure to atomic hydrogen lowers the decomposition temperature of GaAs. Simultaneous exposure of GaAs to atomic hydrogen and atomic nitrogen above 500°C results in a layer rich in GaN. The degree of passivation was monitored by photoluminescence. A fourfold improvement in luminescence efficiency was obtained by nitridization, while a factor-of-ten improvement can be obtained with the more complicated technique of generating an (AlGa)As skin. This research was supported by the Air Force Office of Scientific Research under Contract No. F49620-80-C-0039.     

砷化镓晶片表面的XPS研究

用X射线光电子能谱分析技术（XPS）研究了几种砷化镓抛光片及经不同表面处理方法处理的砷化镓晶片表面的化学计量比和表面化学组成。结果表明砷化镓抛光片的表面自然氧化层中含有Ga2O3、As2O5、As2O3及元素As；表面化学计量比明显富镓，而经过适当的化学处理后这些表面特性能得到较大改善。     

Study of GaAsBi MOVPE growth on (1 0 0) GaAs substrate under high Bi flow rate by high resolution X-ray diffraction

GaAsBi alloy was grown on (1 0 0) GaAs substrate by metalorganic vapour phase epitaxy. GaAsBi film was elaborated with V/III ratio of 9.5, trimethyl bismuth molar flow rate of about 3 μmol/min and a growth temperature of 420 °C. The surface morphology of GaAsBi alloy was investigated by means of scanning electron microscopy and atomic force microscopy. Results show surface Bi droplets formation. High-resolution X-ray diffraction (HRXRD) curves present more diffraction peaks other than that of GaAs substrate. Detailed HRXRD characterization shows that diffraction peaks splitting do not represent a crystallographic tilting with respect to GaAs substrate. Diffraction patterns also show a remarkable stability of the alloy against thermal annealing.     

GaAs surface wet cleaning by a novel treatment in revolving ultrasonic atomization solution

A novel process for the wet cleaning of GaAs surface is presented. It is designed for technological simplicity and minimum damage generated within the GaAs surface. It combines GaAs cleaning with three conditions consisting of (1) removal of thermodynamically unstable species and (2) surface oxide layers must be completely removed after thermal cleaning, and (3) a smooth surface must be provided. Revolving ultrasonic atomization technology is adopted in the cleaning process. At first impurity removal is achieved by organic solvents; second NH_4OH : H_2O_2 : H_2O =1:1:10 solution and HCl : H_2O_2 : H_2O = 1:1:20 solution in succession to etch a very thin GaAs layer, the goal of the step is removing metallic contaminants and forming a very thin oxidation layer on the GaAs wafer surface;NH_4OH : H_2O =1:5 solution is used as the removed oxide layers in the end. The effectiveness of the process is demonstrated by the operation of the GaAs wafer. Characterization of the oxide composition was carried out by X-ray photoelectron spectroscopy. Metal-contamination and surface morphology was observed by a total reflection X-ray fluorescence spectroscopy and atomic force microscope. The research results show that the cleaned surface is without contamination or metal contamination. Also, the GaAs substrates surface is very smooth for epitaxial growth using the rotary ultrasonic atomization technology.