An Overview of the Ultrawide Bandgap Ga2O3 Semiconductor-Based Schottky Barrier Diode for Power Electronics Application

Abstract

Gallium oxide (Ga₂O₃) is a new semiconductor material which has the advantage of ultrawide bandgap, high breakdown electric field, and large Baliga's figure of merit (BFOM), so it is a promising candidate for the next-generation high-power devices including Schottky barrier diode (SBD). In this paper, the basic physical properties of Ga₂O₃ semiconductor have been analyzed. And the recent investigations on the Ga₂O₃-based SBD have been reviewed. Meanwhile, various methods for improving the performances including breakdown voltage and on-resistance have been summarized and compared. Finally, the prospect of Ga₂O₃-based SBD for power electronics application has been analyzed.

Keywords: Baliga’s figure of merit; Breakdown electric field; Gallium oxide (Ga2O3); On-resistance; Power device; Schottky barrier diode (SBD); Ultrawide bandgap semiconductor.

Fig. 1

Transformation relationships among the crystalline phases of Ga2O3 and their hydrates [30]

Fig. 2

The lattice structure of β-Ga₂O₃ crystal. Reprinted from ref. [5]

Fig. 3

Theoretical limits of on-resistance (R_on) as a function of breakdown voltage (V_br) for β-Ga₂O₃ and representative semiconductors. Reprinted from ref. [26]

Fig. 4

The development of Ga₂O₃ SBD in recent years [, , , –71]

Fig. 5

a, b Forward and reverse electric characteristics of the SBD based on (010) β-Ga₂O₃ substrates with different doping concentrations. The lower limit of current density measurment is 10^-8 A/cm². Reprinted from ref. [62]

Fig. 6

a X-ray diffraction (XRD) curve of (100) β-Ga₂O₃ single-crystal substrate, clearly showing the peaks of (400), (600), and (800) planes. b Cross-sectional high-resolution transmission electron microscope (HRTEM) image of Pt/β-Ga₂O₃ Schottky contact and fast Fourier transformed (FFT) micrograph of β-Ga₂O₃ crystal. c Forward and reverse J–V curve of a Pt/β-Ga₂O₃ SBD and the schematic of the SBD (inset). d Forward J–V curve in linear and semi-logarithmic plot. e Temperature-dependent J–V curves and the Richardson’s plot (inset). f Dependence of ON-resistance and forward current density on temperature. Reprinted from ref. [60]

Fig. 7

a Structure of the SBD device based on the HVPE-grown 7-μm-thick n⁻-Ga₂O₃ homoepitaxial drift layer on n⁺-Ga₂O₃ single crystal substrate. b Forward J–V characteristics of the device measured at 21–200 °C. c Reverse J–V at 21–200 °C (solid and dotted lines represent the experimental and simulated results, respectively). Reprinted from ref. [16]

Fig. 8

Fabrication processes of the α-Ga₂O₃ SBD proposed by FLOSFIA Inc. Reprinted from ref. [18, 67]

Fig. 9

a Structure of the SBD with field plate. b, c Forward and reverse electrical characteristics (V_br = 1076 V). Reprinted from ref. [68]

Fig. 10

a Fabrication processes of the MOS-type Ga₂O₃ SBD with trench termination structure. b Comparison of the reverse characteristics of the Ga₂O₃ SBDs with and without trenches. Reprinted from ref. [70]

Fig. 11

a Schematic of the cross-sectional Pt/Ga₂O₃ SBD and p-Cu₂O/n-Ga₂O₃ diode. b Band diagram of the p-Cu₂O/n-Ga₂O₃ interface. c, d Forward and reverse J–V characteristics of the SBD and p-n diode. Reprinted from ref. [71]

Fig. 12

a Rectification circuit. b–e Rectifying effect of Pt/Ga₂O₃ SBD on the AC signals under frequency of 10 kHz, 100 kHz, 500 kHz, and 1 MHz. Reprinted from ref. [63]