Electrical characterization of metal–semiconductor–metal structure of pseudomorphic InGaN on GaN: Simulation and experiments

Fermi level pinning at the free surface together with the Schottky barrier at the end electrodes forms a concave or convex lateral band structure at the surface of polarized nitrides. Experimental results on dark and photo current versus voltage characteristics as well as on responses to a short optical pulse revealed a concave structure for a 20-nm thick InGaN layer with x = 0.13. A moderate polarization of 40% of a calculated value, a surface trap density of 2 x 10(13)/cm(2) located at 0.6 eV below E-c, and a carrier lifetime of 1 ns can reproduce the experimental data. When Fermi level pinning is strong enough, a significant part of small bias voltages is bored by the surface InGaN layer, which results in an ohmic rise of the dark current. (C) 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim