Vol. 43, Issue 1, pp. 47-52 (2013)

Abstract

The rigorous numerical analysis of the surface photovoltage (SPV) versus excitation UV-light intensity (Φ), from 10⁴ to 10²⁰ photon/(cm²s) in a metal/insulator/n-GaN structure with a negative gate voltage (V_G = –2 V) was performed using a finite element method. In the simulations we assumed a continuous U-shape density distribution function D_it(E) of the interface states and n-type doping concentration N_D = 10¹⁶ cm^–3. The SPV signal was calculated and compared in three different characteristic regions at the interface, namely i) under the gate centre, ii) near the gate edge and iii) between the gate and ohmic contact. We attributed the differences in SPV(Φ) dependences to the influence of the interface states in terms of the initial band bending and interface recombination controlled by the gate bias. The obtained results are useful for the design of GaN-based UV-radiation photodetectors.