Switching Performance up to 150°C of β-Ga2O3 Field-Plated Vertical Schottky Diodes for 0.3-1 a Forward Current and 300-900 V Reverse Voltage
Authors: Yang Jiancheng , Carey Patrick H , Ren Fan , Chen Yen-Ting , Liao Yu-Te , Chang Chin-Wei , Lin Jenshan , Tadjer Marko J , Pearton Stephen J. , Kuramata Akito 
Published: February 2020

In the past few decades, wide-bandgap SiC (3.3 eV) and GaN (3.4 eV) based semiconductor rectifiers have shown promising results in power electronic switching and control applications. [1] Recently, Ga2O3 has attracted significant interest for its outstanding potential in power electronics due to superior material properties and availability of high-quality substrate and n-type epistructures. [2,3] The energy band gap of Ga2O3 is in the range of 4.5 – 4.9 eV, which corresponds to a ~8 MV/cm theoretical breakdown electric field. Reverse breakdown voltages larger than 1 kV were reported for both unterminated Ga2O3 vertical rectifiers (1000 V and 1600 V) and field-plated Ga2O3 Schottky diode (1076 V and 2300 V) with an epi thickness of 8 µm and 20 µm, respectively. [4,5,6,7] Furthermore, the switching characteristics of Ga2O3 vertical Schottky diodes were also investigated, and the recovery time was in the range of 20 to 30 ns. [6,7] This indicates an impressive potential application for high power switching devices. In this study, field-plate edge-termination was utilized on a lightly doped 20 µm Ga2O3 epitaxial layer to greatly improve the Ga2O3 vertical rectifier breakdown voltage. In addition, we demonstrate that an 8 µm epitaxial layer of β-Ga2O3 on bulk conducting substrates can achieve forward currents in the 1 A range with a reverse breakdown voltage of 760 V.

Field-plated edge-terminated (FPET) Schottky diodes with a reverse breakdown voltage of 2100 V (0.1 cm × 0.1 cm) and an absolute forward current of 1 A with 760 V of breakdown voltage (Diameter = 0.1 cm) were achieved on 20 and 8 µm epi-Ga2O3, respectively. The recovery characteristics for Ga2O3 FPET Schottky diode switching from forward current of 1 A and 0.3 A to reverse off-state voltage of -300 V and -900 V with recovery time (trr) of 60 ns and 81 ns were demonstrated on diodes with drift layers thickness of 8 µm and 20 µm with 4.4 × 1015 cm-3 and 2.0 x 1015 cm-3 Si-doped epi-Ga2O3 layer, respectively. There was no significant temperature dependence of trr up to 150°C. These results are an important milestone towards the applications of Ga2O3 vertical Schottky rectifiers in high power device and high-speed switching technologies.

References

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