Effect of Interface States on the Performance of Antimonide nMOSFETs

Antimonide (Sb) quantum-well MOSFETs are demonstrated with an integrated high- κ dielectric (1-nm Al₂O₃ /10-nm HfO₂). The effect of interface trap density D_it on the dc drive current and transconductance gm is studied in detail using split C-V/G -V, pulsed I -V, and radio-frequency measurements. Pulsed I-V measurements show improved on current, transconductance, and subthreshold slope due to reduced charge trapping in the dielectric at high frequencies. The long-channel Sb nMOSFET exhibits effective electron mobility of 6000 cm²/V·s at high field (2 × 10¹²/cm² of charge density Ns), which is 15× higher than Si NMOS inversion layer mobility, and one of the highest values reported for III-V MOSFETs. The short-channel Sb nMOSFET (LG = 150 nm) exhibits a cutoff frequency fT of 120 GHz, an fT × LG product of 18 GHz·μm , and a source-side injection velocity v_eff of 2.7 × 10⁷ cm/s at a drain bias V_DS of 0.75 V and a gate overdrive of 0.6 V.