Interface Properties of Metal-Oxide-Semiconductor Structures on 4H-SiC{0001} and (1120) Formed by N_2O Oxidation

摘要

4H-SiC(0001), (0001), and (1120) have been directly oxidized by N_2O at 1300℃, and metal-oxide-semiconductor (MOS) interfaces have been characterized. The interface state density has been significantly reduced by N_2O oxidation on any face, compared to conventional wet O_2 oxidation at 1150℃. Planar n-channel metal-oxide-semiconductor field-effect transistors (MOSFETs) fabricated on 4H-SiC(0001), (0001) and (1120) faces have shown effective channel mobilities of 26, 43, and 73 cm~2/Vs, respectively. Secondary ion mass spectrometry analyses have revealed a clear pileup of nitrogen atoms near the MOS interface. The thickness of the interfacial transition layer can be decreased by N_2O oxidation. The crystal face dependence of the interface structure is discussed. A simple consideration of chemistry indicates that NO, generated from the decomposition of N_2O, may be a more efficient oxidant of carbon than O_2.