Effective mobility enhancement in Al₂O₃/InSb/Si quantum well metal oxide semiconductor field effect transistors for thin insb channel layers

Al2O3/InSb/Si quantum well MOSFETs were fabricated with a thin InSb channel layer grown directly on Si(111) substrates. The InSb thickness ranged from 6 to 25 nm. These thicknesses are close to the critical thickness of InSb on Si, when the InSb layer is grown using a special technique called surface reconstruction controlled epitaxy, which reduces the lattice mismatch from 19.3 to 3.3% by rotating the in-plane InSb axis by 30 with respect to the Si(111) substrate. Good FET characteristics were observed for 10nm InSb channel devices. The dependence of the device properties on InSb channel thickness was investigated. The enhancement of effective mobility for thin InSb channel devices was demonstrated, which indicates the crystal quality improvement when approaching the critical thickness.