Effect of Uniaxial Strain on the Drain Current of a Heterojunction Tunneling Field-Effect Transistor

The electrical characteristics of a heterojunction tunneling field-effect transistor (HETT), with a p-type Si_0.75Ge_0.25 source, have been measured as a function of strain. HETTs with channel transport and applied strain both in the [110] direction show a smooth monotonic change in drain current over a range of 0.09% compressive to 0.13% tensile strain. A measure γ = (d/d ln J_D)(d ln J_D/ds) |_s=0 of the effect of strain s on tunneling current J_D is proposed, which captures the dependence of the tunneling exponential argument on strain. An experimental value of γ = -11.7 is extracted for the tensile case and compared to simulation results. We found theoretically that the value and sign of depend sensitively on the built-in strain at the Si-SiGe interface.