PHOTOREFLECTANCE CHARACTERIZATION OF SEMICONDUCTORS AND SEMICONDUCTOR HETEROSTRUCTURES

The electromodulation method of photoreflectance (PR) is becoming an important tool for the characterization of semiconductors, semiconductor interfaces and semiconductor microstructures such as superlattices, quantum wells, multiple quantum wells and heterojunctions. Since PR is contactless, requires no special mounting of the sample and can be performed in a variety of transparent ambients it can be utilized for in-situ monitoring of growth at elevated temperatures, in-situ elevation at 300K before the samples are removed from the growth/processing chamber as well as convenient ex-situ characterization. This invited article discusses some recent uses of PR to measure (a) the direct gap (and spin-orbit split component) of InP up to 600° C, (b) strains in Si at the Si/SiO2 interface, (c) changes in the surface Fermi level of GaAs caused by photowashing, (d) quantized intersubband transitions in a GaAs/Gao0.82Al0.18As multiple quantum well and (e) two-dimensional electron gas effects in selectively doped n-Gao.7Alo.3As/ GaAs heterostructures. © 1990 The Mineral, Metal & Materials Society, Inc.