A cathodoluminescence study on the diffusion length in AlGaInP/InGaP/AlInP solar cell heterostructures

Abstract

The diffusion length of minority carriers in a p-doped InGaP layer is derived from the cathodoluminescence (CL) intensity profiles. Two procedures are used. First, the CL profile is recorded along a line crossing the intersection between a thin metallic mask and the semiconductor; a second approach consists of the measurement of the intensity profile around an intentional scratch on the surface of the sample. A longer diffusion length is measured when using the metallic mask as compared with the scratch. We discuss the role of non-radiative recombination centers in the reduction of the diffusion length around the scratch. The temperature dependence of the diffusion length is also measured, and the length is found to decrease with temperature.