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

High-mobility strained Ge0.958Sn0.042 p-channel metal-oxide-semiconductor field-effect-transistors (p-MOSFETs) with ammonium sulfide [(NH4)2S] 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. (NH4)2S surface passivation was performed for the GeSn surface, followed by gate stack formation. Ge0.958Sn0.042 p-MOSFETs with (NH4)2S passivation show decent electrical characteristics and a peak effective mobility of 509 cm2/V s, which is the highest reported peak mobility obtained for GeSn channel p-MOSFETs so far.

► Strained Ge0.958Sn0.042 p-channel MOSFETs with (NH4)2S surface passivation are demonstrated. ► The devices showed peak effective hole mobility of 509 cm2/V s. ► At high inversion densities, the mobility remains lower than GeSn p-MOSFETs with Si passivation.