New Optoelectronic Technique for Characterization of Semiconductors

9307419张本研究计划的目标是开发一种新的光电技术的半导体的表征。 这项新技术提供了表面和界面的电子特性以及载波动力学（相位和振幅）的相干测量。 该技术包括使用飞秒激光照射半导体，并测量由于自由载流子光注入半导体中的静态电场和磁场而产生的快速电流瞬变所产生的电磁辐射。 通过测量辐射电场的时域波形，可以用非接触的方法确定静电场的强度和方向。 一个直接的应用是研究生长样品上的半导体表面和界面的静态场的形成动力学。 可以直接监测界面场（场方向和强度）对半导体的影响。 在单分子层外延生长、表面电化学钝化、表面金属化层沉积以及样品从液氦温度到熔化温度的过程中。 现象，如虚载流子人口与界面场和载流子输运（皮秒量子霍尔效应）在高磁场将详细阐述。***

9307419 Zhang The objective of this research plan is to develop a new optoelectronic technique for the characterization of semiconductors. The new technique offers coherent measurement of the electronic properties of surfaces and interfaces, as well as carrier dynamics (both phase and amplitude). The technique consists of using a femtosecond laser to illuminate semiconductors, and measuring the electromagnetic radiation produced by the rapid current transients due to optical injection of free carriers into static electric and magnetic fields in the semiconductors. By measuring the time domain waveform of the radiated electric field, the strength and direction of the static electric field can be determined with a non contact approach. A direct application is studying the formation dynamics of the static fields of semiconductor surfaces and interfaces on as grown samples. The influence of the interface fields (both field direction and strength) on the semiconductor can be monitored directly. During monolayer epitaxial growth, surface electrochemical passivation, ultrathin metallic layer deposition, as well as when the sample goes from the liquid helium temperature to its melting temperature. Phenomena such as virtual carrier population associated with the interface field and carrier transport (picosecond quantum Hall effect) at high magnetic fields will be elaborated upon. ***