Real-time reflectance anisotropy spectroscopy of GaAs homoepitaxy.

Reflectance anisotropy spectroscopy (RAS) is a highly sensitive optical probe for the real-time study of the epitaxial growth of zincblende semiconductors. Here we report on (1) non-equilibrium RAS spectra acquired in real time during the homoepitaxial growth of GaAs, and (2) RAS spectra for GaAs surfaces under equilibrium with several arsenic overpressures. We show that in both cases RAS spectra can be decomposed into two basic components, each with a characteristic line shape.

A rapid reflectance-difference spectrometer for real-time semiconductor growth monitoring with sub-second time resolution.

We report on a rapid, 32-channel reflectance-difference (RD) spectrometer with sub-second spectra acquisition times and ΔR/R sensitivity in the upper 10(-4) range. The spectrometer is based on a 50 kHz photo-elastic modulator for light polarization modulation and on a lock-in amplifier for signal harmonic analysis. Multichannel operation is allowed by multiplexing the 32 outputs of the spectrometer into the input of the lock-in amplifier.

Microreflectance difference spectrometer based on a charge coupled device camera: surface distribution of polishing-related linear defect density in GaAs (001).

We describe a microreflectance difference (microRD) spectrometer based on a charge coupled device (CCD), in contrast to most common RD spectrometers that are based on a photomultiplier or a photodiode as a light detector. The advantage of our instrument over others is the possibility to isolate the RD spectrum of specific areas of the sample; thus topographic maps of the surface can be obtained. In our setup we have a maximum spatial resolution of approximately 2.

Measurement of the surface strain induced by reconstructed surfaces of GaAs (001) using photoreflectance and reflectance-difference spectroscopies.

We report photoreflectance-difference and reflectance-difference measurements on reconstructed GaAs (001) surfaces. From these data the linear and quadratic electro-optic coefficient spectra are determined in the important 2.8-3.