Influence of the thickness of frontal platinum metallic layer on the electro-optical characteristics of GaN-based Schottky ultraviolet photodetectors

In this work, we evaluated the effect of the thickness of frontal metallic layer on the electro-optical characteristics of an n-type gallium nitride (n-GaN)-based Schottky barrier ultraviolet (UV) detector using device modeling and numerical simulations. Comparison of the current density-voltage characteristics J(V) calculated for different metals demonstrated that platinum (Pt) is the most suitable metal to form Schottky contacts. The obtained results show that the thickness of the frontal platinum Schottky contact highly affects the spectral responsivity of the detector in the considered UV range of 0.2...0.4 mu m. In particular, the detector responsivity at room temperature can reach the peak value of 0.208 A center dot W-1 at the wavelength of 0.364 mu m and the semi-transparent Pt layer as thin as 1 nm. Afterward, it gradually decreases with the increase of the metal layer thickness down to 0.147 A center dot W-1 for the thickness of the Pt layer of 100 nm.