Time-Resolved Depletion Region Carrier Dynamics at Semiconductor Surfaces & Interfaces

最近，我们进行了一个时间分辨实验，清楚地证明了表面空间电荷场对砷化镓中耗尽区载流子动力学的影响。这些研究可以潜在地深入了解半导体表面和埋藏半导体界面附近的载流子输运特性，以及在亚微米器件中，表面空间电荷场跨越大部分（如果不是全部）半导体器件结构。我们提出了几个重要的实验研究的新扩展。首先，我们建议利用可变波长探针脉冲来增强我们现有的测量技术。这将允许我们在实验中改变表面空间电荷区域内的信息深度，促进枯竭区载流子运输的更定量的理论模型。其次，我们希望将我们的测量扩展到包括其他系统，例如硅器件结构，GaAs/ZnSe埋地接口和半导体/金属接口。第三，我们希望将我们的测量扩展到可变泵浦强度范围，使我们能够包括表面或界面空间电荷场的光电调制效应。这些测量将提供半导体表面或界面上筛选过程动力学的详细图像，使我们能够分析直接靠近界面的掺杂密度不均匀的结构。

Recently we performed a time-resolved experiment which clearly demonstrates the effect of the surface space-charge field on the depletion region carrier dynamics in GaAs. These studies can potentially yield considerable insight into carrier transport properties near semiconductor surfaces and buried semiconductor interfaces, and in submicron devices, where the surface space-charge field spans most, if not all, of the semiconductor device structure. We propose several important new extensions of our experimental studies. First, we propose to enhance our current measurement technique by utilizing variable wavelength probe pulses. This will permit us to vary our information depth within the surface space-charge region in our experiments, facilitating a more quantitative theoretical model of the depletion region carrier transport. Second, we would like to extend our measurements to include other systems, such as silicon device structures, GaAs/ZnSe buried interfaces, and semiconductor/ metal interfaces. Third, we would like to extend our measurements into the variable pump intensity regime, enabling us to include photomodulation effects of the surface or interface space-charge field. These measurements will provide a detailed picture of the dynamics of the screening process at a semiconductor surface or interface, enabling us to analyze structures with inhomogeneous dopant densities directly adjacent to an interface.