Electroreflectance, photoreflectance, and photoabsorption properties of polycrystalline CdTe thin films prepared by the gradient recrystallization and growth technique

In this work we report electroreflectance, photoreflectance, and photoabsorption measurements on CdTe polycrystalline thin films. These thin films were prepared by the gradient recrystallization and growth technique. The measurements were performed around the fundamental energy gap of the semiconductor at room temperature. The energy gap of this polycrystalline material coincides with that corresponding to the single-crystal material, and the phenomenological energy broadening parameter is larger than that corresponding to the single-crystal semiconductor by a factor of three, approximately. The photoabsorption signal is obtained by studying the origin of a low-energy peak which appears in the photoreflectance spectrum.