Surface Chemistry and Kinetics of the Metalorganic Chemical Vapor Deposition of II-VI Materials

摘要：本文研究了金属有机化学气相沉积（MOCVD）技术沉积碲化镉锌合金薄膜的表面化学性质。它包括表征薄膜在砷化镓或锗（001）表面成核和生长时的原子结构和组成。合金生长动力学是由超高真空（UHV）表面科学实验、薄膜沉积速率的宏观测量和MOCVD过程的数值模拟相结合确定的。利用特高压扫描隧道显微镜研究了碲化镉锌在砷化镓或锗（001）上的异质外延，监测了每层原子沉积过程中界面结构的演变。利用透射电子显微镜和光致发光测量来评价薄膜的质量。II-VI化合物的外延薄膜，如碲化镉锌，被用于各种光电和磁性器件。金属有机化学气相沉积（MOCVD）是一种很有前途的沉积这些薄膜的方法。然而，在制造环境中，这是一个具有挑战性的过程，因为薄膜的生长速度和组成取决于固有反应动力学，使它们对操作条件非常敏感。这一努力为II-VI化合物半导体薄膜的可重复性生长提供了必要的基础知识。＊＊＊

ABSTRACT CTS-9631785 This is a study of the surface chemistry underlying the deposition of cadmium zinc telluride alloy films by metallorganic chemical vapor deposition (MOCVD). It includes characterizing the atomic structure and composition of the film as it nucleates and grows on a gallium arsenide or a germanium (001) surface. Alloy growth kinetics are determined by a combination of ultrahigh vacuum (UHV) surface-science experiments, macroscopic measurements of film deposition rates, and numerical simulations of the MOCVD process. The heteroepitaxy of cadmium zinc telluride on gallium arsenide or germanium (001) is studied using a UHV scanning tunneling microscope to monitor the evolution of the interface structure as each layer of atoms is deposited. The quality of the films is evaluated using transmission electron microscopy and photoluminescence measurements. Epitaxial thin films of II-VI compounds such as cadmium zinc telluride are used in a variety of optoelectronic and magentic devices. Metallorganic chemical vapor deposition (MOCVD) is a promising method for depositing these films. However, it is a challenging process in a manufacturing environment because the film growth rate and composition depend on the intrinsic reaction kinetics, making them very sensitive to the operating conditions. This effort provides the basic knowledge needed to provide reproducible growth of thin films of II-VI compound semiconductors. ***