Low-resistance and transparent ohmic contacts are formed by using a strained p-In0.15Ga0.85N (3 nm thick) capping layer and oxidized Ni (5 nm)/Au (5 nm) scheme. Unlike as-deposited Ni/Au contacts to p-GaN (without the strained p-InGaN), as-deposited contacts to InGaN/GaN produce ohmic behaviour. Upon annealing, the Schottky barrier height (SBH) of the contacts to the InGaN/GaN is reduced down to 0.29 eV and so the samples yield a contact resistivity as low as 6.3 × 10-6 Ω cm 2. In addition, the annealed contacts give a light transmittance of 86% at a wavelength of 460 nm. Possible ohmic formation mechanisms for the Ni/Au contacts to InGaN/GaN are described in terms of a reduction of SBH, an increase of surface carrier concentration and the formation of a NiO:Au structure.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Electrical and Electronic Engineering
- Materials Chemistry