V-Pits and Trench-Like Defects in High Periodicity MQWs GaN-Based Solar Cells: Extensive Electro-Optical Analysis

By combining microscopy investigation, light-beam induced current (LBIC), microphotoluminescence (μ -PL), and micro-electroluminescence (μ -EL) characterization, we investigate the electrical and optical properties of V-pits and trench-like defects in highperiodicity InGaN/GaN multiple quantum wells (MQWs) solar cells. Experimental measurements indicate that V-pits and their complexes are preferential conductive paths under reverse and forward bias. Spectral analysis shows a redshifted wavelength contribution, with respect to MQWs emission peak wavelength, in presence of agglomerates of V-pits surrounded by trench-like defects.The intensity of the redshifted wavelength contribution is more pronounced under μ -EL with respect to μ -PL characterizations, due to the localization of carrier flow in proximity of V-defects. Results give insight on the role of V-pits and their agglomerates on the electrical and optical properties of high-periodicity quantum well structures, to be used for InGaN-based photodetectors and solar cells.