Influence of barrier thickness on the performance of InGaN/GaN multiple quantum well solar cells

The performance of InGaN/GaN multiple quantum well (MQW) solar cells containing 15 periods of 2.7 nm thick In0.21Ga0.79N wells and three different GaN barriers thicknesses of 3.0 nm, 6.3 nm, and 10.0 nm is investigated. Increasing barrier thickness results in absorption at lower energies, consistent with piezoelectric polarization induced electric fields tilting the energy bands of the MQW and changing the transition energy of well states. The internal quantum efficiency and leakage currents are additionally affected by GaN barrier thickness, resulting in the 6.3 nm barrier structure achieving the highest power conversion efficiency (1.66%, 1 sun AM1.5G). (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3695170]