GaSb p-Channel Metal-Oxide-Semiconductor Field-Effect Transistors with Ni/Pt/Au Source/Drain Ohmic Contacts

GaSb is an attractive candidate for future high-performance III–V p-channel metal-oxide-semiconductor-field-effect-transistors (pMOSFETs) because of its high hole mobility. The effect of HCl based-chemical cleaning on removing the non-self limiting and instable native oxide layer of GaSb to obtain a clean and smooth surface has been studied. It is observed that the rms roughness of a GaSb surface is significantly reduced from 2.731 nm to 0.693 nm by using HCl:H₂O (1:3) solution. The Ni/Pt/Au ohmic contact exhibits an optimal specific contact resistivity of about 6.89×10^?7 Ω?cm² with a 60 s rapid thermal anneal (RTA) at 250°C. Based on the chemical cleaning and ohmic contact experimental results, inversion-channel enhancement GaSb pMOSFETs are demonstrated. For a 6 μm gate length GaSb pMOSFET, a maximum drain current of about 4.0 mA/mm, a drain current on-off (ION/IOFF) ratio of >103, and a subthreshold swing of ～250 mV/decade are achieved. Combined with the split C–V method, a peak hole mobility of about 160 cm²/V?s is obtained for a 24 μm gate length GaSb pMOSFET.