Elevated barrier height originated from electric dipole effect and improved breakdown characteristics in PtO<sub>x</sub>/<i>β</i>-Ga<sub>2</sub>O<sub>3</sub> Schottky barrier diodes
Guangzhong Jian, Weibing Hao, Zhongyu Shi, Zhao Han, Kai Zhou, Qi Liu, Qiming He, Xuanze Zhou, Chen Chen, Yanguang Zhou, Xiaolong Zhao, Guangwei Xu, Shibing Long
Abstract
Abstract The higher Schottky barrier height of PtO x / β -Ga 2 O 3 Schottky barrier diode (SBD) was derived from the electric dipole effect of PtO x Schottky electrode. And the higher Schottky barrier height effectively improved the reverse breakdown characteristics of β -Ga 2 O 3 SBD. In this work, PtO x / β -Ga 2 O 3 and Pt/ β -Ga 2 O 3 SBDs were fabricated, and the Schottky barrier height of PtO x SBD increased with the increment of oxygen element component in PtO x 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 PtO x layer thickness in Pt/PtO x / β -Ga 2 O 3 SBDs, the Schottky barrier height increased from 1.32 eV to 1.82 eV. Bright-field scanning transmission electron microscopy image demonstrated that PtO x 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 PtO x SBD. Lower leakage current density, higher breakdown voltages and more concentrated breakdown voltage distribution were obtained for PtO x SBDs. Furthermore, the barrier heights of PtO x 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 PtO x / β -Ga 2 O 3 SBD had great potential in enhancing reverse blocking characteristics and high-temperature environment applications.