The properties of GaAs-Al 2O 3 and InP-Al 2O 3 interfaces and the fabrication of MIS field-effect transistors

Abstract

The interface properties of InP and GaAs metal-insulator-semiconductor (MIS) structures with Al 2O 3 as the gate insulator were investigated. The Al 2O 3 film was deposited by the pyrolysis of aluminium isopropoxide (Al(OC 3H 7) 3). The surface state density of the InP-Al 2O 3 MIS structure is of the order of 10 11 cm -2 eV -1 and is 2–5 times lower than that of the GaAs MIS structure. The static characteristics of fabricated MIS field-effect transistors (FETs) show a well-defined pinch-off region. There is no leakage current at the gate electrode. The electron mobility in the channel was determined from the static characteristics to be 750 cm 2 V -1 s -1 for InP MISFETs and 2100 cm 2 V -1 s -1 for the GaAs MISFETs. The results show that the MIS structure has an advantage over the Schottky contact as the gate of an InP FET.