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

The heteroepitaxy process for growing thin films of single crystal \beta -phase gallium oxide ( \beta -Ga ₂ O ₃) 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 -Ga ₂ O ₃ results in improving the surface morphology, which reduces contact resistance between the source/drain electrode and \beta -Ga ₂ O ₃. Experimental results show that the \beta -Ga ₂ O ₃ 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