Study of surface electrical properties of InAlGaAs structures grown on InP substrates

摘要

Room temperature photoreflectance (PR) was used to investigate the energy gaps transition, the surface state densities and the surface barrier height of In__xAl_yGai._(x.y)As, in a series of epitaxial surface intrinsic-n+ structures with different Al concentration. Features of Franz-Keldysh oscillations originating from the built-in electric field in the intrinsic top layer were observed. Based on the thermionic emission theory and current-transport theory, the surface state density can be determined from the square of maximum electric field as a function of various pump beam flux intensities.