Using the contactiess modulation spectroscopy technique of photoreflectance, the
temperature variations of the direct gap E0 of GaAs, InP, GaA1As, InGaAs have
been measured at elevated temperatures up to 600°C. The parameters which describe
the temperature dependence of the band gap energies have been evaluated.
The ability to measure the band gap at elevated temperatures opens up many new
possibilities for in-situ monitoring of MBE and MOCVD processes. In this paper,
we review some of the recent developments in the use of photoreflectance at