High-Mobility Stable 4H-SiC MOSFETs Using a Thin PSG Interfacial Passivation Layer

Phosphorous from P
₂
O
₅
is more effective than nitrogen for passivating the 4H-SiC/SiO
₂
interface. The peak value of the field-effect mobility for 4H-SiC metal-oxide-semiconductor field-effect transistors (MOSFETs) after phosphorus passivation is approximately 80 cm
²
/V·s. However, P
₂
O
₅
converts the SiO
₂
layer to phosphosilicate glass (PSG)-a polar material that introduces voltage instabilities which negate the benefits of lower interface trap density and higher mobility. We report a significant improvement in voltage stability with mobilities as high as 72 cm
²
/V·s for MOSFETs fabricated with a thin PSG gate layer ( ~ 10 nm) capped with a deposited oxide.