GaInN/GaN p‐i‐n light‐emitting solar cells

Abstract

AbstractGaInN/GaN p‐i‐n double‐heterojunction structures were grown by metal‐organic vapor phase epitaxy on c‐plane sapphire substrates, and light‐emitting solar cells with different GaInN active layer thicknesses were fabricated. The thickness of the GaInN active layer was varied from 100 to 400 nm, while the thickness of both n‐type and p‐type GaN layers was kept constant. A semitransparent ohmic contact to p‐type GaN was formed by electron‐beam evaporation of Ni/Au (5 nm/5 nm). The film thickness of p‐GaN was 50 nm. The external quantum efficiency (EQE) of the device with a 400 nm GaInN layer exceeded 60% at a wavelength of approximately 380 nm. The transparency of the Ni/Au electrode was 68%. Therefore, the internal quantum efficiency of this device exceeded 95%. Note that this device emitted green light when a forward voltage was applied. The electroluminescence peak wavelength was approximately 525 nm, which was much longer than the EQE peak wavelength. The origin of this large emission shift is discussed. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)