Structural and electrical characterizations of the pulsed-laser-deposition- grown Sc_2O_3/GaN heterostructure

摘要

Single-crystalline Sc_2O_3 was grown on GaN/sapphire template using pulsed laser deposition and the interface characteristics of the Sc_2O_3/GaN heterostructure were investigated. An epitaxial relationship of [112]_(Sc_2O_3)||[2130]_(GaN) and (222)_(Sc_2O_3)||(0002)_(GaN) was revealed by x-ray diffraction and cross-sectional transmission electron microscopy. A valence band offset of 0.84 eV was obtained by x-ray photoelectron spectroscopy, indicating a conduction band offset of 2.04 eV across the Sc_2O_3/GaN heterointerface. In addition, a low interface state density of 4 X 10~(11) eV~(-1) cm~(-2) was estimated from capacitance-voltage measurements. The epitaxial nature with good interface characteristics has rendered a substantially low leakage current of 1 μA/cm~2 at a reverse gate bias of 30 V in the Sc_2O_3/GaN metal-oxide-semiconductor structures.