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), micro-photoluminescence (
$\mu $
-PL), and micro-electroluminescence (
$\mu $
-EL) characterization, we investigate the electrical and optical properties of V-pits and trench-like defects in high-periodicity 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
$\mu $
-EL with respect to
$\mu $
-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.