Enhancement-Mode Antimonide Quantum-Well MOSFETs With High Electron Mobility and Gigahertz Small-Signal Switching Performance

This letter demonstrates, for the first time, enhancement-mode (e-mode) antimonide MOSFETs by integrating a composite high-κ gate stack (3 nm Al₂O₃ -1 nm GaSb) with an ultrathin InAs_0.7Sb_0.3 quantum well (7.5 nm). The MOSFET exhibits record high electron drift mobility of 5200 cm²/V · s at carrier density (N_s) of 1.8 × 10¹² cm^-2, subthreshold slope of 150 mV/dec, I_ON/I_OFF ratio of ~4000× within a voltage window of ~1 V, high I_ON of 40 μA/μm at V_DS of 0.5 V for a 5-μm gate length (L_G) device. The device exhibits excellent pinchoff in the output characteristics with no evidence of impact ionization enabled by enhanced quantization and e-mode operation. RF characterization allows extraction of the intrinsic device metrics (C_gs, C_gd, g_m, v_eff and f_t) and the parasitic resistive and capacitive elements limiting the short-channel device performance.