Al_(2)O_(3) prepared by atomic layer deposition as gate dielectric on 6H-SiC(0001)

摘要

Al_(2)O_(3) films were deposited as alternative gate dielectric on hydrogen-terminated 6H-SiC(0001) by atomic layer chemical vapor deposition and characterized by photoelectron spectroscopy (PES) and admittance measurements. The PES results indicate an abrupt interface free of significant Si-suboxide contributions where the Al_(2)O_(3) layer is connected to SiC by bridging oxygen atoms. The admittance measurements yield an interface state density which is lower than that of the thermally formed oxide and show in particular no increase toward the conduction band edge. Furthermore, a nearly symmetrical band alignment of Al_(2)O_(3) on 6H-SiC with offsets of 2.2 and 1.8 eV is determined for the valence and conduction bands, respectively. This makes Al_(2)O_(3) a serious competitor to thermal oxides as gate insulator in SiC devices.