High-Speed Steep-Slope GaInAs Impact Ionization MOSFETs (I-MOS) With SS = 1.25 mV/dec—Part I: Material and Device Characterization, DC Performance, and Simulation
Daxin Han, Giorgio Bonomo, Diego Calvo Ruiz, Akshay M. Arabhavi, Olivier Ostinelli, C. R. Bolognesi
Abstract
Digital electronics power consumption evolved into a major concern: at the current pace, general-purpose computing energy consumption will exceed global energy production before 2045. The principal approach to curbing energy consumption in digital applications calls for ``steep-slope'' devices with an inverse subthreshold slope (SS) parameter well below the ``ln(10)·kT/q'' limit of conventional electronics (60 mV/dec at 300 K). Impact ionization MOSFETs (I-MOS) provide an avenue for steep-slope device realization. High-mobility narrow gap III-V semiconductor channel materials have not yet been investigated for I-MOS applications. We hereby report E-mode narrow bandgap GaInAs-based I-MOS devices with an SS of 1.25 mV/dec maintained over five orders of magnitude in drain current and <formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex>$I_{{on}}$</tex> </formula> / <formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex>$I_{{off}}$</tex> </formula> ratios >10⁶ at 300 K (>10⁹ at 15 K) for a gate length of <formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex>$L_{G} $</tex> </formula> = 100 nm. Part I of this work focuses on the materials and device fabrication and analysis, device dc characterization, and modeling. The present GaInAs devices are the first I-MOS transistors to display a robust steep-slope effect at low voltages <formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex>$V_{DS} $</tex> </formula> < 1.9 V at 300 K and <1 V at 15 K. Part II describes the dynamic switching (including clarifications on the role of hysteresis) and RF characteristics of GaInAs I-MOS devices and benchmarks them with respect to other steep-slope technologies.