The influence of high dielectric constant aluminum oxide sputter deposition on the structure and properties of multilayer epitaxial graphene

High dielectric constant aluminum oxide (Al2O3) is frequently used as the gate oxide in high electron mobility transistors and the impact of its deposition by radio frequency (RF) magnetron sputtering on the structural and electrical properties of multilayer epitaxial graphene (MLG) grown by graphitization of silicon carbide (SiC) is reported. Micro-Raman spectroscopy and temperature dependent Hall mobility measurements reveal that the processing induced changes to the structural and electrical properties of the MLG can be minimal when the oxide deposition conditions are optimal. High-resolution transmission electron microscopy (HRTEM) analysis confirms that the Al2O3/MLG interface is relatively sharp and that our thickness approximation of the MLG using angle resolved x-ray photoelectron spectroscopy (ARXPS) is accurate. An interface trap density of 5.1 x 1010 eV-1 cm-2 was determined using capacitance-voltage techniques. The totality of our results indicates that ARXPS can be used as a nondestructive tool to measure the thickness of MLG, and that RF sputtered Al2O3 can be used as a high dielectric (high-k) constant gate oxide in multilayer graphene based transistor applications.