Chemical and Physical Rate Processes in GaN Chemical Vapor Deposition

在本研究中，将详细研究化学气相沉积（CVD）工艺中生产GaN膜的气相动力学。重点将放在氮气和三甲基镓以及氨和三乙基镓气相沉积过程中发生的均相气相反应上。两种实验方法将被采用：(1)激光驱动的均匀热解将用于气相动力学和(2)光学成像的垂直浓度分布的生长表面将用于研究重要的生长物种。反应性中间浓度分布将使用激光诱导荧光成像。该实验程序将与从头算分子轨道计算相结合，结合过渡态理论来估计实验研究中未确定的次要反应的速率系数。本项目开发的气相机制将与表面反应的文献信息相结合，并纳入CVD反应器模型。这些研究与用于照明、光数据存储和其他应用的GaN发光二极管和二极管激光器的发展有关。氮化镓是用化学气相沉积法生产的；然而，大多数技术都是通过经验手段开发的。这项研究应该有助于对基本过程的基本理解。

In this study detailed gas-phase kinetics for the production of GaN films in a chemical vapor deposition (CVD) process will be developed. The focus will be on the homogeneous gas-phase reactions that occur during CVD of GaN from NH3, and trimethylgallium and from NH3 and triethylgallium. Two experimental methods will be used: (1) laser powered homogeneous pyrolysis will be employed for the gas-phase kinetics and (2) optical imaging of vertical concentration profiles above growth surfaces will be used for investigations of important growth species. Reactive intermediate concentration profiles will be imaged using laser induced fluorescence. This experimental program will be complemented with ab initio molecular orbital calculations in combination with transition state theories to estimate rate coefficients for less important reactions not determined in the experimental studies. The gas-phase mechanism developed in this project will be combined with literature information on surface reactions and incorporated into a CVD reactor model. These studies are relevant to the development of GaN light emitting diodes and diode lasers for lighting, for optical data storage and for other applications. GaN is grown commercially by CVD; however, most techniques have been developed by empirical means. This study should contribute to a fundamental understanding of the basic processes.