Performance enhancement of GaAs UTB pFETs by strain, orientation and body thickness engineering

III-V semiconductors can provide a viable option for continuous scaling of future CMOS technology [1-3]. We report a significant enhancement in the ON-current (I_ON) of ultra-thin body (UTB) GaAs intrinsic channel p-MOSFETs using biaxial compressive strain. Our theoretical investigation shows that valence bands (VB) become hyperbolic under compressive strain in GaAs rendering effective mass approximation (EMA) invalid. The ballistic I_ON (~Q_inv (hole density) × V_inj (injection velocity)) is governed mainly by the asymptotic group velocity (V_grp ~ α.V_inj) of the hyperbolic VBs, These bands can be engineered using GaAs body thickness (T_ch) scaling, compressive strain value and wafer orientation. V_inj is primarily controlled by strain and T_ch whereas, Q_inv is governed mainly by the gate electrostatics, thus providing two separate design parameters to control I_ON. Isotropic strain enhances V_inj which gives a maximum improvement in I_ON of ~23-40% for [100]/(100) and [110]/(111) pMOSFETs for 5 nm body thickness at 4% compressive biaxial strain. Scaling body thickness from 5nm to 2nm improves ION by ~2X for all the device orientations considered in this study.