An Al-Drain Silicon Transistor With Ultra-Steep Subthreshold Slope and Low Operating Voltage

Abstract

A mainstream silicon-based field effect transistor (FET) with sub-60mV/Dec subthreshold swing (SS) is long desired for ideal switching. In this letter, we experimentally demonstrated a novel silicon SOI MOSFET with Al drain, namely AlD-FET. The measurements show that the new device achieves an ultra-steep average SS of $15~\mu $ V/dec over 7 decades with high I $_{\text {ON}} \gt 10~\mu $ A/ $\mu $ m @ V $_{\text {DS}} = 1$ V, and the operating voltage for a sharp SS to occur can be as low as 0.4V. TCAD simulation reveals that the electrical field at Al-Silicon Schottky drain junction is significantly enhanced, and the depletion region under Al drain is elongated. Both facilitate a stronger impact ionization effect at a low VDS to take place, and the additional positive feedback loop further enables the nearly ideal sharp switching.