Determination of the mean and the homogeneous barrier height of Cu Schottky contacts on heteroepitaxial β-Ga2O3 thin films grown by pulsed laser deposition

We have investigated the electrical properties of Cu Schottky contacts (SCs) on (2̄01)-oriented β-Ga2O3 thin films, which have been grown by pulsed laser deposition (PLD). The I-V characteristics of two different sample structures exhibit rectification ratios at ±2 V up to 7 orders of magnitude. The dominant current transport mechanism is thermionic emission. By fitting the I-V characteristics, we obtained the ideality factor n and the effective barrier height ΦBeff at temperatures between 50 and 320 K. Considering a Gaussian barrier height distribution, we determined a mean barrier height of 1.32 eV. The contacts are stable at high temperatures up to at least 550 K. At this temperature a homogeneous barrier height of 1.32 eV is found, consistent with the determined mean barrier height. The ideality factor for this temperature is 1.03 and barrier inhomogeneities do not influence current transport, making the contact close to ideal. Schematic band diagram of a Cu/β-Ga2O3 Schottky contact at a temperature of 550 K. The inset shows a photographic image of the sample. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.