Impact of Structural Properties on the Mechanisms of Optical Amplification in Cubic GaInN

The structural and the optical properties of cubic GaInN MBE-grown on GaAs substrates are investigated using scanning electron- and cathodoluminescence microscopy, time-resolved and time-integrated photoluminescence spectroscopy as well as gain measurements at 2 K and 300 K. The In content is ranging from 3% to 30%. From the carrier dynamics localized states are proposed to be responsible as recombination mechanism. From temperature- and intensity-dependent gain measurements, the identification of the gain processes was possible. Optical gain values up to 60 cm(-1) were observed at wavelengths up to 500 nm, indicating the advantage of this material system due to the lack of detrimental pyro- and piezoelectric fields. The degree of In fluctuations directly determines the optical quality and the efficiency of optical amplification of the samples.