Carrier escape mechanism dependence on barrier thickness and temperature in InGaN quantum well solar cells

The properties of quantum well carrier escape were studied by varying barrier thicknesses in InGaN/GaN multi-quantum well solar cell devices. The dependence of the photocurrent on applied bias and temperature exhibited properties indicative of the quantum well carrier escape mechanisms of thermionic emission and tunneling, with tunneling dominating for thin barriers and high fields. Simulations using a self-consistent drift-diffusion and Schrödinger solver with analytical formulas extracted carrier escape lifetimes. By employing sufficiently thin barriers, it was found that escape lifetimes can be made small compared to recombination lifetimes, leading to high internal quantum efficiency.