The splitting of heavy and light holes due to the indium-induced strain in3-inch indium-alloyed semi-insulating GaAs substrates

Room temperature photoreflectance (PR) was used to determine the splitting of the heavy and light holes in the edge region of 3-inch diameter semi-ins ulating (SI) bulk indium-alloyed GaAs materials grown by the liquid-encapsu lated Czochralski (LEC) method. The shift of heavy hole energy is larger in the edge region of wafer compared to the central region. This non-uniformi ty is attributed to the radial distribution of indium; Indium content being higher and lower, respectively, around the edge region and at the central area. In addition, when the indium content reaches a critical point, we fin d the splitting of the heavy and light holes near the edge of the GaAs wafe r due to the indium-content variation induced strain in the process of grow ing GaAs substrate. The variation of heavy hole energy indicates that of th e indium content in the wafer and the separation between the heavy and ligh t holes is attributed to the different indium content in adjacent regions w here indium content varies rapidly.