Mitigating Band Tail Effects by Electrostatic Doping in SOI Hybrid Gate MOSFETs

A novel method to mitigate cryogenic band tail effects is proposed by applying electrostatic doping in the prototype hybrid gate devices. The π-gate/GAA hybrid architecture facilitates independent back bias control over the channel beneath the π-gate. By applying forward back bias (FBB), the source-channel junction is shifted toward the π-gate/GAA interface, thereby spatially separating the junction from the defect-rich region. The hybrid gate device realizes an average subthreshold swing (SS) of ~16mV/dec at 15K with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">bg</sub>≥10V, outperforming uniform GAA devices and effectively suppressing the SS inflection. At 4.2K, the average SS further improves to ~12mV/dec with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i><sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">bg</sub>≥25V, supporting up to a 40% reduction in the supply voltage (V<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dd</sub>). These findings indicate that the dopant-induced band tail states could be effectively screened by electrostatic doping, providing a promising strategy for SS optimization in energy-efficient computing.