Self-consistent analysis of lattice-matched and pseudomorphic quantum-well emission transistors

A self-consistent analysis of the quantum-well emission transistor (QWET) is presented allowing an exact calculation of the device quantum properties. Poisson’s and Schrcdinger’s equation are solved numerically using a finite-difference method on a self-consistent basis. Pseudomorphic AlGaAs/InGaAs designs with 150/o-20% excess In are suggested for improving the device performance. Design with doping in various parts of the QWET are also studied. This analysis reveals that the device performance is less optimistic than previously predicted by analytic approaches. By introducing the pseudomorphic channel principle,,while maintaining a reasonably low Al content for the gate and collector layers, it is, however, possible to obtain satisfactory performance. Optimum pseudomorphic designs showed high current driving capability (2 X lo5 A/cm’), high transconductance (3S/mm) and small intrinsic delay time (2 ps).