Influence of fixed charges and trapped electrons on free electron mobility at 4H-SiC(0001)/SiO2 interfaces with gate oxides annealed in NO or POCl3

Abstract

Free electron mobility ( μ _free ) in 4H-SiC(0001) MOSFETs with gate oxides annealed in NO or POCl _3 was calculated in a wide range of effective normal field ( E _eff ) from 0.02 to 2 MV cm ^−1 , taking account of scattering by fixed charges and trapped electrons. The present calculation indicates that the Hall mobility in the high- E _eff region experimentally obtained for NO-annealed MOSFETs (14 cm ^2 V ^−1 s ^−1 at 1.1 MV cm ^−1 ) is much lower than that for POCl _3 -annealed MOSFETs (41 cm ^2 V ^−1 s ^−1 ) due to severe Coulomb scattering by electrons trapped at a very high density of interface states.

Keywords

• silicon carbide
• metal-oxide-semiconductor
• field-effect transistors
• electron scattering
• hall effect
• mobility calculation