Comparison of optoelectrical characteristics between Schottky and Ohmic contacts to $\beta-Ga_{2}O_{3}$ thin film

Schottky and Ohmic contacts are key matters affecting carrier transport in oxide semiconductor based electrical and optical devices. For Ga2O3, the comparison of optoelectrical behaviors and the fundamental physical mechanism between these two contacts are not well known yet. In this work, β-Ga2O3 thin films were grown via metal-organic chemical vapor deposition then deposited with symmetrical Ni/Au (Schottky) or Ti/Au (Ohmic) contacts. Optoelectrical measurements show that the Ohmic contacted device exhibits superior responsivities thanks to their higher photocurrents. While for the Schottky contacted device, firstly, it has faster response speed, secondly it exhibits larger photo-to-dark current ratios owing to their low dark current. Specifically, the voltage- and light intensity-dependent responsivity and detectivities of the Schottky and Ohmic contacted devices were measured and discussed under the consideration of different voltages and UV light intensities.