Correlation between structural properties and optical amplification in InGaN/GaN heterostructures grown by molecular beam epitaxy

We comprehensively studied InGaN/GaN heterostructures grown by molecular beam epitaxy (MBE) using a variety of methods of optical spectroscopy, such as cathodoluminescence microscopy (CL), time-integrated and time-resolved photoluminescence. To correlate the fluctuations in emission wavelength with values for the optical amplification we performed gain measurements in edge-stripe geometry. The lateral homogeneity can be drastically improved using a template of GaN grown on the sapphire substrate by metal-organic vapor phase epitaxy (MOVPE). Gain values up to 62 cm −1 were found in samples with low indium fluctuations, which is comparable to values for high-quality InGaN/GaN heterostructures grown by MOVPE.