Theoretical study of performance limits in nano-scale InAs HEMTS based on quantum-corrected Monte Carlo method

We theoretically estimate the performance limits of the effective injection velocity, v_s, and f_T in the nano-scale InAs HEMTs using the quantum-corrected Monte Carlo (MC) method. The negative tail of the momentum distribution function, f(x, k_x) at the potential bottleneck is caused by the electron scatterings. As L_g decreases, the negative tail decreases: which results in the increase of v_s. Because of the lower effective mass of InAs, the InAs HEMTs show higher v_s than those in the InGaAs HEMTs and the Si MOSFETs. At L_g = 10 nm, v_s is estimated to be about 4.4 times 10⁷ cm/s, which is almost reaching the ballistic limit. We calculate the delay time distribution, tau (x), and define the effective gate length, L_{g, eff}, on the basis of tau (x). Then we estimate the upper limit of f_T, f_{T, max}, by extrapolating f_T to the lower limit of L_{g, eff}. f_{T, max} is 3.6 THz for the InAs HEMTs, which improves from 3.0 THz for the InGaAs HEMTs. These results indicate the superior potential of the InAs HEMTs for future logic, communication and terahertz applications.