Optical study of clustering in III-V semiconductor quaternary solid solutions

Abstract

Multicomponent epitaxially grown III-V semiconductor solid solutions are frequently non-uniform, but have a tendency of clustering. Optical studies can be used to reveal the complex internal structure of the epitaxial layer. Here we analyze the temperature dependence of the linear polarization of the photoluminescence (PL) emission from different GaInP and GaInAsP epilayers in a temperature range from 10 K to 300 K. At room temperature the PL emission is not polarized, whereas at low temperature the PL emission from the GaInAsP epilayers is linearly polarized with a degree of polarization of approximately 0.2 at 10 K. When the temperature increases, the PL polarization decreases and becomes insignificant at approximately 100–150 K. Additionally, from 10 K to 100 K, the temperature dependence of the energy of the GaInAsP PL emission peak maximum follows a characteristic S-shaped curve. We calculated the PL polarization degree taking into account the change in crystal symmetry caused by local biaxial and uniaxial strain in the emitting clusters. According to the calculations, the PL emission from uniaxially strained regions is polarized and the strain depends on temperature, which is consistent with the measured data. These results show that the epitaxial GaInAsP solid solution is not homogeneous, but includes elastically strained clusters, which are consequence of atomic content fluctuations.