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Keywords:

  • III-V semiconductors;
  • chemical vapor deposition;
  • solar cells

Abstract

GaInN/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)