Over 3 kV and ultra-low leakage vertical (011) <b> <i>β</i> </b> -Ga2O3 power diodes with engineered Schottky contact and high-permittivity dielectric field plate

Abstract

We report over 3 kV breakdown voltage and ultra-low leakage (011) β-Ga2O3 power devices utilizing Schottky barrier engineering and high-permittivity (κ) dielectric (ZrO2) field plate. The (011) orientation of β-Ga2O3 enabled low background doping and thick drift layers, which are promising to support kV class vertical β-Ga2O3 power switches. The Schottky barrier engineering was performed with a composite Pt cap/PtOx/Pt (1.5 nm) anode contact to take advantage of the enhanced reverse blocking capabilities enabled by PtOx while allowing low turn-on voltage by the interfacing thin Pt layer. We also performed a systematic study using a co-processed Pt/(011) β-Ga2O3 Schottky barrier diodes (SBDs) on the same wafer. The bare SBDs revealed a breakdown voltage of ∼1.5 kV, while the field-plate Pt/(011) β-Ga2O3 SBDs achieved an increased breakdown voltage of 2.75 kV owing to the edge field management. Further enhancement of the breakdown voltage was achieved by tunneling leakage management using composite Pt cap/PtOx/Pt (1.5 nm) Schottky contacts that ultimately enabled a breakdown voltage of 3.7 kV for the field-plate diodes. Remarkably, the Pt cap/PtOx/Pt (1.5 nm) Schottky contacts maintained a similar turn-on voltage as the Pt/(011) β-Ga2O3 SBDs. The combination of efficient tunneling leakage management by composite Pt cap/PtOx/Pt (1.5 nm) contacts with similar turn-on voltage, edge field reduction by high-κ dielectric ZrO2 field plate, as well as the advantageous material properties offered by (011) β-Ga2O3 demonstrates a promising strategy for developing ultra-low leakage and multi-kV class vertical (011) β-Ga2O3 power devices.