Micron thick Gd2O3 films for GaN/AlGaN metal–oxide–semiconductor heterostructures

Abstract

One µm thick Gd 2 O 3 films were grown on GaN/AlGaN heterostructures by reactive electron beam physical vapor deposition. The films were of cubic bixbyite phase with strong (222) out-of-plane and in-plane texture. The films showed a columnar microstructure with feather-like growth. Transmission electron microscopy analysis and selected area diffraction showed highly oriented single crystal like growth near the film interface which degraded as the film thickness increased. Capacitance-voltage (C-V) characteristics show that the Gd 2 O 3 device results in a negative threshold shift of approximately 1.9 V. Hysteresis of 0.9 V was extracted from the C-V curve corresponding to a trapped charge density of 6.9 x 10 10 cm-2. The conduction mechanisms were found to be dominated by Poole Frenkel conduction between 50-100 °C and Schottky emission between 125-200 °C. The trap height for Poole-Frenkel conduction was 0.46 eV and the Schottky barrier height was 0.79 eV.