Thermoreflectance study of the direct energy gap of GaSb

We studied the optical properties of high quality GaSb layers, grown by molecular beam epitaxy, in the region of the fundamental gap E-0 using thermoreflectance spectroscopy in the temperature range between 80 and 300 K. The experimental line-shapes were analyzed with a functional form model including excitonic effects. Taking advantage of the derivative-like nature of the thermoreflectance spectroscopy, an accurate determination of the temperature dependence of the energy gap E-0(T) is obtained, which is well reproduced by the semi-empirical Varshni relation. (C) 1997 Elsevier Science Ltd.