Presidential Young Investigators Award: Surface Chemistry In Semiconductor Thin Film Deposition

实验计划将联合收割机常规表面 分析技术与新的激光为基础的方法来检查表面 薄半导体的化学气相沉积（CVD）中的化学 薄膜，特别是砷化镓薄膜。 这些激光技术 包括光反射（PR）和表面二次谐波产生 （SHG）。 它们将用于检查以下各个步骤： 吸附、表面扩散和解吸 沉积机理 表面键能，表面扩散 系数和吸附物相互作用将被测量。 的 CVD的表面化学仍然实际上是未知的。 这种缺乏 理解可能是由于相互作用的弱点， 气体和半导体。 环境压力大于10-4 Torr 往往需要诱导显着的化学反应，但在这些 大多数传统的表面分析工具（其采用 带电粒子）失效。 PR和SHG尚未被广泛使用， 在这种压力下是有效的。高空间分辨率 （~0.5微米）使得这些技术特别适合于 测量表面扩散。 这些数据目前 不存在的半导体，即使表面扩散是 预期在许多沉积反应中是限速的。 表面化学控制杂质的掺入，缺陷的形成， 低温生长速率，以及许多其他沉积现象， 对于薄半导体膜的制造至关重要。 可靠的表面反应速率和机制对于 智能CVD反应器设计 对于镓来说尤其如此 砷化物，目前的试错法电影 增长只产生了好坏参半的结果;潜在的应用 砷化镓用于高速电路和光电子器件 对于通信来说，需要做出重大努力来理解 表面生长现象

Experiments are planned that will combine conventional surface analytical techniques with new laser-based methods to examine surface chemistry in the chemical vapor deposition (CVD) of thin semiconductor films, particularly of gallium arsinide. These laser techniques include photoreflectance (PR) and surface second harmonic generation (SHG). They will be used to examine the individual steps of adsorption, surface diffusion, and desorption in the overall deposition mechanism. Surface bond energies, surface diffusion coefficients, and adsorbate interactions will be measured. The surface chemistry of CVD remains virtually uncharted. This lack of understanding may result from the weakness of the interactions between gases and semiconductors. Ambient pressures greater than 10-4 Torr are often required to induce significant chemistry, but at these pressures most conventional surface analytical tools (which employ charged particles) fail. PR and SHG have not been widely employed but are effective at such pressures. Furthermore, high spatial resolution (~0.5 micron) makes these techniques particularly suited for measurements of surface diffusion. Such data are currently nonexistent for semiconductors, even though surface diffusion is expected to be rate-limiting in many deposition reactions. Surface chemistry controls impurity incorporation, defect formation, low-temperature growth rates, and many other deposition phenomena that are vitally important to the manufacture of thin semiconductor films. Reliable surface reaction rates and mechanisms are crucial for intelligent CVD reactor design. This is particularly true for gallium arsinide, for which the current trial-and-error approach to film growth has yielded only mixed results; the potential application of gallium arsinide to high-speed circuits and to optoelectronic devices for communications warrants a major effort toward the understanding of surface growth phenomena.