Study of the band offset in InxGa1-xAs/GaAs system using photoreflectance of single quantum wells

In order to gain information about the band offset in the strained layer InGa1As/GaAs system we have investigated photorefleCtanCe (PR) from two single quantum wel 1 samples at 300 K and 77 K. Our samples have we 1 1 width L= 110 A (sample 1) and L = 107 A (sample 2) with In Composition x = 0. 11 (sample 1 ) and x = 0. 19 (sample 2 ) . We have observed a number of intersubband transitions in the spectra of both samples. By studying the polarization dependence of the PR at 300 K using an internal reflection mode we have identified spectral features Corresponding to light and heavy hole to conduction subband transitions. Good agreement between our experimental results and an envelope function calculation (including strain) is obtained for conduction band offset Q = 0.45 0.07 (sample 1) and Q = 0.67 0.07 (sample 2). These values comply with the compositional dependence of proposed by Joyce et al [Phys.Rev. B 38, 10978 (1988)1.