Investigation of carbon interstitials with varied SiO2 thickness in HfO2/SiO2/4H-SiC structure

Abstract

The electrical performance of SiC-based devices is strongly affected by the border traps of high-k dielectrics and carbon (C) interstitials in SiC. The abrupt HfO2/ SiC junction exhibits frequency dispersion in capacitance–voltage (C-V) curves. The thin SiO2 (7.5 nm) sample that is without excess C clusters exhibits ideal C-V characteristics. With the increase of SiO2 thickness, excess C in SiC substrates is detected by using both auger electron spectroscopy and x-ray photoelectron spectroscopy. The thick SiO2 (15.5 nm) sample contains enormous excess C inside SiC close to SiO2 interface, and excess C changes the substrates to n+-like behavior.