Hydrogen removal by annealing from C-doped InGaAs grown on InP by metalorganic chemical vapor deposition

Hydrogen removal from C-doped InGaAs grown on InP substrate by metalorganic chemical vapor deposition is discussed based on the dependence of hole concentration on various annealing conditions. It is revealed that the hydrogen removal rate becomes higher as the annealing temperature is higher and the activation energy of hydrogen removal is about 1.9 eV regardless of C-doped layer thickness. The hydrogen removal rate is also found to be inversely proportional to C-doped layer thickness, suggesting that the hydrogen removal reaction is mainly governed by hydrogen diffusion.     

The influence of window layers on the performance of 650 nm AlGaInP/GaInP multi-quantum-well light-emitting diodes

In this article, we investigate the influence of AlGaAs and GaP window layers on the device performance of 650 nm AlGaInP/GaInP multi-quantum-well (MQW) light-emitting diodes (LEDs) grown by metalorganic chemical-vapor deposition. The AlGaInP/GaInP MQW structure with different window layers are characterized by double-crystal X-ray diffraction, secondary ion mass spectrometry and photoluminescence. By using the AlGaAs window layer, the LEDs have a lower cut-in voltage, a smaller dynamic series resistance and a higher breakdown voltage, while the LEDs with a GaP window layer show a stronger electroluminescence intensity, a higher light output power, a higher external quantum efficiency and a slower degradation of light output with increasing bias current. These results indicate that the GaP material is more adequate to be used as a window layer for the AlGaInP optical devices.     

Size, position and direction control on GaAs and InAs nanowhisker growth

The self-organized, position-controlled and parallel growth of GaAs and InAs nanowhiskers is successfully demonstrated by using a metal–organic chemical vapour deposition method. The growth takes place preferentially along the 111 As direction with the aid of the catalytic effect of Au nanodroplets, and not along 111 Ga or In directions. The diameter and length of the whisker can be controlled artificially down to 10 nm and to over 1 μm, respectively. Doping and composition control of p- or n-type such as GaAs–InAs heterostructure formation are possible along the length direction of the whisker by changing the source gases. In order to control the growth position of the whisker, positioning of a Au nanodroplet is essential and realized by a lithographic method. By choosing the [111]B direction to the substrate surface and normal to the patterned side edges, and by positioning the Au nanodroplet on the side wall, the positioned planar nanowhisker growth and bridging are successfully demonstrated. The growth mechanism of the nanowhiskers is revealed by the scanning and transmission electron microscope observations. Nanometer-size Au-alloy droplets play an important role in the growth of the whiskers. The whisker growth process is governed by the vapor–liquid–solid growth mechanism.     

Synthesis and characterization of methylcyclopentadienyl‐(η3‐allyl)platinum and its use as a metallo‐organic chemical vapour deposition precursor of platinum

This communication reports on rapid, efficient synthesis of the metal‐organic chemical vapor deposition (MOCVD) precursor (methylcyclopentadienyl)allylplatinum. The compound is shown to be an effective precursor for the deposition of platinum thin films giving deposits of high quality and purity, probably due to the nature of ligands which seems to be good leaving <?tw=99%>groups as confirmed by mass spectrometric path‐­way. Copyright © 1999 John Wiley & Sons, Ltd.     

MOCVD-InAs/GaSb DBR结构材料的特性研究

本研究采用MOCVD技术在GaSb衬底上制备InAs与GaSb交替生长层构成的分布布喇格反射镜(DBR)材料.由于InAs与GaSb材料晶格匹配良好,且折射率差较大,因此用这两种材料交替生长构成的DBR结构,在较低生长周期时即可获得较高的反射率.将其引入共振腔增强型红外探测器结构,做为共振腔的腔体,将大大改善器件性能,实现红外光的高灵敏度室温探测.根据多膜增反原理,膜层反射率随膜层周期增加而增加,理论计算结果显示InAs/GaSb DBR结构工作波长为2.4μm,周期为22时,膜层反射率即可高于80.11;.我们用扫描电子显微镜,X-ray射线衍射,反射光谱测量等分析手段,对InAs/GaSb DBR结构材料的物理性能进行表征.结果表明,我们已经成功获得高质量的晶格匹配的InAs、GaSb单晶薄膜,以及InAs/GaSb交替生长组成的不同周期的DBR结构材料.反射光谱测量显示,InAs/GaSb DBR反射率随膜层周期数增加而增加,当InAs/GaSb DBR周期数为22时,其反射率约为44.27;.     

Effect of annealing in N2 atmosphere on net acceptor concentration in ZnSe:N grown by MOCVD

Annealing effect on net acceptor concentration in ZnSe:N is investigated. ZnSe:N homo-epitaxial layer was grown at 823 K by MOCVD using ammonia (NH₃) as a dopant source. Photoluminescence (PL) spectra measured on as-grown layer exhibited the strong deep donor–acceptor pair (D^dAP) emission and the weak I₁^N emission line. In order to enhance the activation of nitrogen in ZnSe epitaxial layer, sample was annealed at the 823 K in nitrogen (N₂) and hydrogen (H₂) atmosphere. Only the annealing in nitrogen atmosphere increased I₁^N emission intensity indicate the activation of nitrogen acceptor. And net acceptor concentration was estimated to be 3 × 10¹⁷cm⁻³ by C–V measurements. This activation mechanism is interpreted as hydrogen is released from N–H bonds during annealing in nitrogen atmosphere.     

AlInGaN材料的生长及其光学性质的研究

研究AlInGaN材料的生长特性及其光学性质.通过对不同生长温度生长的三个AlInGaN样品的 测量，发现In的掺入量随着生长温度的降低而增加，而Al的掺入几乎没什么变化；在较低温 度下生长的材料具有较好的材料质量与光学特性，其原因直接与In组分的掺入有关，In组分 的掺入可以减少材料的缺陷，改善材料的质量.同时，用时间分辨光谱研究了AlInGaN材料的 发光机理，发现其发光强度随时间变化（荧光衰退寿命）不是指数衰减，而是一种伸展的指 数衰减.通过对这种伸展的指数衰减特性的研究，发现AlInGaN发光来自 关键词： AlInGaN MOCVD 局域激子 量子点     

原位生长高度定向ZnO晶须

采用大气压金属有机化合物化学气相沉积(AP-MOCVD)方法，以Zn(C₅H₇O₂)₂为原料，在玻璃基片上制备出高度定向的ZnO晶须.扫描电子显微镜观察发现晶须垂直基片取向生长，规则排列，长度、形状几乎一致.晶须直径为100nm—800nm,长径比为8—15，尖端曲率半径仅为50nm，甚至更小.x射线衍射(XRD)分析结果表明ZnO晶须为六方晶系纤锌矿结构，并沿c轴高度取向.采用热分析对反应前驱物进行了研究,同时也讨论 关键词： ZnO 取向生长 晶须 MOCVD     

Metal alkoxides and β-diketonates as precursors for oxide and non-oxide thin films

Single-components or multicomponent oxide thin films are of interest for electronic and opto-electronic devices, optical applications, catalysis, corrosion protection etc. Their preparation by chemical routes is based on the hydrolytic (sol-gel process) or pyrolytic (MOCVD) conversion of precursors. Derivatives having M? O bonds, namely metal alkoxides, carboxylates or β-diketonates, are the most common sources of metal oxides. The properties of alkoxides are appropriate for sol-gel as well as MOCVD applications, whilst the limited hydrolytic susceptibility but good volatility of β-diketonates is most convenient for MOCVD purposes. The low temperature and flexibility of sol-gel routes, and the presence of residual OH groups in the final films, are favorable for the encapsulation of organic or organometallic derivatives, the anchoring of enzymes and in general for the development of functional and composite coatings. The facile formation of heterometallic alkoxides is also attractive for the development of coatings based on multimetallic formulations. MOCVD is favorable for the buildup of heterostructures and epitaxial layers. Although metal alkoxides and β-diketonates are usually oxide precursors, nitride or sulfide films can be obtained by reacting with the appropriate reagents. Fluorinated ligands enhance volatility but often result in the formation of metal fluorides.