SnO/β-Ga2O3 heterojunction field-effect transistors and vertical p–n diodes

In this work, we report on the realization of SnO/β-Ga2O3 heterojunction vertical diodes and lateral field-effect transistors for power electronic applications. The p-type semiconductor SnO is grown by plasma-assisted molecular beam epitaxy on n-type (100) β-Ga2O3 with donor concentrations of 3 × 1017 cm−3 for the diode devices and 8.1 × 1017 cm−3 for the field-effect transistors. The deposited films show a predominant SnO (001) phase featuring a hole concentration and a mobility of 7.2 × 1018 cm−3 and 1.5 cm2/V s, respectively. The subsequent electrical characterization of the heterojunction diodes and field-effect transistors show stable switching properties with on/off current ratios >106 and specific on-resistances below 4 mΩ cm2. Furthermore, breakdown measurements in air of the non-field-plated heterojunction transistor with a gate-to-drain distance of 4 μm yield a breakdown voltage of 750 V, which equals an average breakdown strength of nearly 1.9 MV/cm. The resulting power figure of merit is calculated to 178 MW/cm2 demonstrating state-of-the-art properties. This emphasizes the high potential of this heterojunction approach.