Atomic-Layer-Deposition HfO2-Based InP n-Channel Metal-Oxide-Semiconductor Field Effect Transistor Using Different Thicknesses of Al2O3 as Interfacial Passivation Layer

Abstract

The effects of ALD deposited HfO2 as the gate dielectric devices on InP substrate using different thicknesses of Al2O3 (5 cycles and 10 cycles respectively) as interfacial passivation layer (IPL) have been investigated. Without Al2O3 as the IPL, MOSFET devices with 50 cycles of HfO2 gate dielectric (with an EOT about 1.3 nm) has a subthreshold swing about 108 mV/dec and drive current 7.87 mV/mm at Vd= 2.5 V, and Vg=Vth+2 V for 20 μm gate length. Compared with single HfO2, the use of Al2O3 as interfacial layer results in better interface quality with the InP substrate. For stacked 10 cycles Al2O3/18 cycles HfO2 devices (EOT also about 1.3 nm), substhreshold swing is decreased to 92.5 mV/dec, and drive current is increased to 20.59 mA/mm at Vd= 2.5 V, and Vg=Vth+2 V for 20 μm gate length.