Strained germanium–tin (GeSn) p-channel metal-oxide-semiconductor field-effect-transistors (p-MOSFETs) with ammonium sulfide passivation

Abstract High-mobility strained Ge 0.958 Sn 0.042 p-channel metal-oxide-semiconductor field-effect-transistors (p-MOSFETs) with ammonium sulfide [(NH 4 ) 2 S] surface passivation were demonstrated. A ∼10 nm thick fully-strained single crystalline GeSn layer was epitaxially grown on Ge (1 0 0) substrate as the channel layer. (NH 4 ) 2 S surface passivation was performed for the GeSn surface, followed by gate stack formation. Ge 0.958 Sn 0.042 p-MOSFETs with (NH 4 ) 2 S passivation show decent electrical characteristics and a peak effective mobility of 509 cm 2 /V s, which is the highest reported peak mobility obtained for GeSn channel p-MOSFETs so far.