Modulation-Acceptor-Doped SiGe Schottky Barrier Field-Effect Transistors

Modulation acceptor doping allows for the generation of holes as free charge carriers in the semiconductor by introducing acceptor states in the gate oxide. This overcomes the limitations of nanoscale doping and maintains the characteristics of impurity-free semiconductor channels. Here, we demonstrate modulation doping via Al-induced acceptor states in a SiO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> gate-dielectric of a SiGe-based Schottky barrier field-effect transistor. Compared to an undoped reference sample, pulsed and temperature-dependent electrical measurements revealed a 4170-times higher conductivity of the ungated SiGe channel and a 3-fold increase in the p-type on-state current when the device is operated as a transistor. Importantly, the application of modulation doping to Ge-rich SBFETs may contribute to nanoscale devices with lower supply voltages and faster switching speeds.