In-situ monitoring of GaSb, GaInAsSb, and AlGaAsSb

Suitability of silicon photodiode detector arrays for monitoring the spectral reflectance during epitaxial growths of GaSb, AlGaAsSb, and GaInAsSb, which have cutoff wavelengths of 1.7, 1.2, and 2.3 {micro}m, respectively, is demonstrated. These alloys were grown lattice matched to GaSb in a vertical rotating-disk reactor, which was modified to accommodate near normal reflectance without affecting epilayer uniformity. By using a virtual interface model, the growth rate and complex refractive index at the growth temperature are extracted for these alloys over the 600 to 950 nm spectral range. Excellent agreement is obtained between the extracted growth rate and that determined by ex-situ measurement. Optical constants are compared to theoretical predictions based on an existing dielectric function model for these materials. Furthermore, quantitative analysis of the entire reflectance spectrum yields valuable information on the approximate thickness of overlayers on the pregrowth substrate