GaSb p-Channel Metal-Oxide-Semiconductor Field-Effect Transistors with Ni/Pt/Au Source/Drain Ohmic Contacts
WU Li-Shu1,2, SUN Bing2, CHANG Hu-Dong2, ZHAO Wei2, XUE Bai-Qing2, ZHANG Xiong1, LIU Hong-Gang2**
1Advanced Photonics Center, School of Electronic Science and Engineering, Southeast University, Nanjing 210096 2Microwave Device and IC Department, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029
Abstract：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.
2012, Vol. 29 
