| We have studied novel transport mechanisms that are of interest and importance for the development of high speed electronic and optoelectronic devices, namely, (i) transport in compensated GaAs and the Double Ridley-Watkins-Hilsum-Gunn effect, (ii) ballistic transport, (iii) focusing electrons and injection of focused energetic electron beam, (iv) double injection in field-effect transistor, (v) electron-to-hole preferential tunneling (vi) distortion of impurity states created by superlattice, (vii) lightening hole effective mass and changing other material parameters by quantum confinement in low-dimensional structures.; These mechanisms are of interest because of the new and exciting physics and because of possible applications. As examples of such applications, we discuss the trapezoidal shaped Gunn domain resulting from the Double Ridley-Watkins-Hilsum-Gunn Effect in compensated GaAs, the Double Base Hot Electron Transistor, the Double Injection Field-Effect Transistors, and the Tunneling Emitter Bipolar Transistor. To study the physics of these novel transport mechanisms, we use the conventional semiconductor equations for structures with large dimensions (e.g. in our studies of DIFET's, where dimensions are larger than 1{dollar}mu{dollar}m), the Monte Carlo method for the transport properties in bulk GaAs and transient transport in structures of small dimensions (e.g. in the studies of HET's and DBHET's, the dimensions are several hundreds or thousands angstroms), and the variational method as well as the {dollar}{lcub}bf kcdot p{rcub}{dollar} perturbation envelope function method for structures of even smaller dimensions (e.g. 2-D and 1-D structures, quantized states in one or two directions). |
