Point defect diffusion in III-nitrides: A key mechanism for thermal degradation and non-radiative recombination in GaInN/GaN quantum well structures

Abstract

Various forms of thermal degradation of light emitters based on III-nitrides have been observed, with no clear conclusion about the mechanism. We investigate the non-radiative carrier lifetime in GaInN/GaN single quantum wells (SQWs) with various emission wavelengths and its relation to the growth conditions. We observe that the non-radiative lifetime in SQWs increases exponentially with decreasing buffer and cladding layer growth temperature. As a first conclusion, diffusion of point defects leading to non-radiative recombination is a universal mechanism present during III-nitride growth. Second, this is likely a predominant mechanism for thermal degradation observed while growing layers on top of the quantum well, e.g., a p-layer, and after post-growth annealing. Performance and reliability of devices can be improved by properly controlling point defect diffusion.