Elevated barrier height originated from electric dipole effect and improved breakdown characteristics in PtOx/β-Ga2O3 Schottky barrier diodes

Abstract

The higher Schottky barrier height of PtOx/β-Ga2O3 Schottky barrier diode (SBD) was derived from the electric dipole effect of PtOx Schottky electrode. And the higher Schottky barrier height effectively improved the reverse breakdown characteristics of β-Ga2O3 SBD. In this work, PtOx/β-Ga2O3 and Pt/β-Ga2O3 SBDs were fabricated, and the Schottky barrier height of PtOx SBD increased with the increment of oxygen element component in PtOx electrode, which were all higher than the Schottky barrier height of Pt SBD. Kelvin probe force microscope measurement indicated that Fermi level pinning effect and the variation in work functions of Schottky electrodes were irrelevant to the higher barrier height. Moreover, with the increment of inserting PtOx layer thickness in Pt/PtOx/β-Ga2O3 SBDs, the Schottky barrier height increased from 1.32 eV to 1.82 eV. Bright-field scanning transmission electron microscopy image demonstrated that PtOx was mainly polycrystal with layer structure near the Schottky interface. The layer structure composed of Pt ions and O ions induced electric dipole effect, and the electric dipole effect led to the increase of Schottky barrier height for PtOx SBD. Lower leakage current density, higher breakdown voltages and more concentrated breakdown voltage distribution were obtained for PtOx SBDs. Furthermore, the barrier heights of PtOx SBDs gradually increased as the temperature raised, resulting in their reverse leakage current increased much more slowly with temperature than that of Pt SBD. The above results demonstrated that PtOx/β-Ga2O3 SBD had great potential in enhancing reverse blocking characteristics and high-temperature environment applications.