Investigation of asymmetric effects due to gate misalignment, gate bias and underlap length in III–V heterostructure underlap DG MOSFET

In the present work, we investigate the influence of asymmetry in III–V heterostructure underlap DG MOSFET caused by back gate movement, back gate voltages and drain side underlap length. The device has narrowband In0.53Ga0.47As and wideband InP layers in the channel, along with high-K Al2O3 as the gate dielectric. The 2D Sentaurus TCAD simulations are done using drift diffusion model and interface traps are considered. The simulation model is calibrated with the previous reported experimental results. For the same gate misalignment value, back gate shift toward drain (BG_D) resulted in a lower DIBL, Ioff and Delay, than back gate shift towards source (BG_S). Conversely, BG_S results in lower SS, higher Ion and Ion/Ioff ratio. Excellent threshold voltage controllability, reduced delay, reduced energy delay product, higher Ion/Ioff ratio are achieved by varying back gate voltage. Varying drain underlap reduces DIBL, SS, Delay, Ioff and increases Vt and Ion/Ioff ratio. Thus, application specific optimized device parameters can be achieved with asymmetrical device structure, asymmetrical gate bias or its combination.

► Device uses narrowband In0.53Ga0.47As and wideband InP layers for body.
► BG_D provide lower DIBL, Ioff, Delay & BG_S provide lower SS, higher Ion, Ion/Ioff.
► Varying drain underlap reduces DIBL, SS, Delay, Ioff and increase Vt, Ion/Ioff.
► 4T configuration provide excellent Vt, subthreshold leakage, delay control.
► 4T reduces energy delay product and provides higher Ion/Ioff.