Photovoltaic Response of InGaN/GaN Multiple-Quantum Well Solar Cells

We report on the fabrication and photovoltaic characterization of In0.12Ga0.88N/GaN multi-quantum-well (MQW) solar cells grown by metalorganic vapor phase epitaxy on (0001) sapphire substrates. Increasing the number of MQWs in the active region from 5 to 30 improves a factor of 10 the peak external quantum efficiency of the device at the price of a slight reduction and increase of the shunt and series resistance, respectively. Solar cells with 30 MQWs exhibit an external quantum efficiency of 38% at 380 nm, an open circuit voltage of 2.0 V, a short circuit current density of 0.23 mA/cm(2) and a fill factor of 59% under 1 sun of AM1.5G-equivalent solar illumination. Solar cells with the grid spacing of the top p-contact varying from 100 to 200 mu m present the same device performance in terms of spectral response and conversion efficiency. (C) 2013 The Japan Society of Applied Physics