Characterization of InGaN-based photovoltaic devices by varying the indium contents

InGaN-based photovoltaic structures with different indium contents in InGaN active layer were investigated. The peak wavelengths of the photoluminescence (PL) spectra were measured at 464.3 nm and 525.4 nm for the blue-photovoltaic device (B-PV) and the green-photovoltaic device (G-PV) structures, respectively. The flat-band voltage was observed at -8 V through the lower temperature (10 K) bias-dependent PL measurement in B-PV device, but the flat-band voltage cannot be observed in G-PV device when the reverse bias was larger than -15 V. The piezoelectric field (PZ) of the G-PV device was larger than the B-PV device through the bias-dependent PL measurement that was caused by the large lattice mismatch between the GaN and InGaN layers with high indium content. The small open-circuit voltage and the larger short-circuit current density (J(sc)) were measured in the G-PV device compared with the B-PV device. The large J(sc) value of the G-PV device was caused by the large photocurrent escaped from the PZ-field induced tilted-band structure in InGaN active layer. The InGaN-based PV devices with a large indium content and a lager PZ field had potential for the InGaN photovoltaic device applications. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.