High κ dielectric single-crystal monoclinic Gd2O3 on GaN with excellent thermal, structural, and electrical properties

Abstract

MBE-grown single-crystal Gd2O3 epitaxially on GaN has exhibited excellent thermal stability, withstanding rapid thermal annealing (RTA) at 1100 °C. The high-κ dielectric Gd2O3 thin film 10 nm thick has a monoclinic phase with a high degree of crystallinity, characterized by X-ray diffraction using synchrotron radiation. The orientation relationship is (over(4, -) 0 2)Gd2 O3 {norm of matrix} (0 0 0 1)GaN and 〈 0 1 0 〉Gd2 O3 {norm of matrix} 〈 2 over(1, -) over(1, -) 0 〉GaN. Interface between Gd2O3 and GaN remains atomically sharp after the RTA, as demonstrated using X-ray reflectivity and high-resolution transmission electron microscopy. Gd2O3/GaN metal-oxide-semiconductor capacitors show well-behaved capacitance-voltage characteristics with small dispersion and hysterisis, a high dielectric constant of ∼17, and a low electrical leakage current density of 4.6×10-9 A/cm2 at 1 MV/cm. © 2008 Elsevier B.V. All rights reserved.