Heteroepitaxial Growth of Sn δ-Doped β-Ga₂O₃ MOSFETs on c-Plane Sapphire via Nonvacuum Mist-CVD Process

Abstract

The heteroepitaxy process for growing thin films of single crystal $\beta $ -phase gallium oxide ( $\beta $ -Ga2O3) on c-plane sapphire substrates was conducted using nonvacuum process mist-chemical vapor deposition. The Sn delta ( $\delta $ )-doping technique was employed to improve the doping concentration, output current, and gate controllability. The use of tetramethylammonium hydroxide (TMAH) to treat the surface of $\beta $ -Ga2O3 results in improving the surface morphology, which reduces contact resistance between the source/drain electrode and $\beta $ -Ga2O3. Experimental results show that the $\beta $ -Ga2O3 MOSFET with Sn $\delta $ -doped layer exposed for 80 s and treatment with TMAH for 5 min proposed in this work exhibit excellent electrical properties, including ${V}_{\text {TH}}$ of −7.5 V, ${I}_{\text {DS},\max }$ of 3.71 mA/mm, a subthreshold swing (SS) of 313.26 mV/dec, ${R}_{\text {on},\text {sp}}$ of $0.6~\Omega \cdot \text {cm}^{{2}}$ , anoff-state breakdown voltage of 1085 V, and a power figure of merit (PFOM) of 1.96 MW/cm2.