High-Speed Steep-Slope GaInAs Impact Ionization MOSFETs (I-MOS) With SS = 1.25 mV/dec—Part II: Dynamic Switching and RF Performance

Part I of this work described narrow bandgap GaInAs-based I-MOS devices with a minimum steep slope $SS_{min}$ = 1.25 mV/dec maintained over 4 orders of magnitude in drain current, ${I}_{ \mathrm{\scriptscriptstyle ON}}/{I}_{ \mathrm{\scriptscriptstyle OFF}}$ ratios >10⁶ at 300 K (>10⁹ at 15 K), and low operating voltages for a gate length of ${L}_{G} $ = 100 nm. Part II focuses on the device time-domain switching capabilities and RF performance. Digital switching tests using a hybrid connected inverter reveal excellent capabilities for high clock rate operation. Simple circuit estimates indicate that the present 100 nm GaInAs I-MOS can operate with clock frequencies >10 GHz. The impact-ionization-induced hysteresis in the ${I}_{D}$ – ${V}_{GS}$ I-MOS characteristics does not play any role in dynamic switching of a digital inverter: the ${n}$ -channel pull-down transistor turns on with a steep slope, but turns off classically with a higher threshold voltage which reduces the dynamic power dissipation per switching cycle. Factors impacting GaInAs I-MOS reliability are considered, and a physically motivated approach to enhance the reliability of III–V MOSFETs is proposed. We show that GaInAs-based I-MOS devices offer high analog cutoff frequencies and low-noise characteristics, suggesting applicability for digital and RF applications on a single technological platform. When benchmarked against other steep-slope technologies, GaInAs I-MOS shows the strongest steep slope, competitive ${I}_{ \mathrm{\scriptscriptstyle ON}}/{I}_{ \mathrm{\scriptscriptstyle OFF}}$ ratios, and lowest operating voltage of any I-MOS transistor to date, without any back-gate/substrate bias.