The analysis of multiband quantum transport simulation in double-gate metal oxide semiconductor field effects transistors (DG-MOSFETs) is performed based on a non-equilibrium Green's function (NEGF) formalism coupled self-consistently with the Poisson equation. The empirical sp3s* tight binding approximation (TBA) with nearest neighbor coupling is employed to obtain a realistic multiband structure. The effects of non-parabolic bandstructure as well as anisotropic features of Si are studied and analyzed. As a result, it is found that the multiband simulation results on potential and current profiles show significant differences, especially in higher applied bias, from those of conventional effective mass model.

Simulation of multi-band quantum transport based on a non-equilibrium Green's functions is presented in resonant tunneling diodes (RTD's), where realistic band structures and space charge effect are taken into account. To include realistic band structure, we have used a multi-band (MB) tight binding method with an sp3s* hybridization. As a result, we have found that the multiband nature significantly changes the results of conventional RTD simulations specifically for the case with indirect-gap barriers.

We describe progress we have achieved in the development of our quantum transport modeling for nano-scale devices. Our simulation is based upon either the non-equilibrium Green's function method (NEGF) or the quantum correction (QC) associated with density gradient method (DG) and/or effective potential method (EP). We show the results of our modeling methods applied to several devices and discuss issues faced with regards to computational time, open boundary conditions, and their relationship to self-consistent solution of the Poisson-NEGF equations. We also discuss those for efficiently tailored QC Monte Carlo techniques.

As a general approach to analyse the field effects on a quantum well with arbitrary potential distribution, a method based upon finite element is presented. The field dependence of the resonant width and the effective energy gap is analysed for quantum wells with potential deformation around the center of wells.

An enhanced temperature dependence of drain saturation current as well as threshold voltage is observed for ion-implanted GaAs MESFET's when backgate or sidegate bias voltage is applied. By performing conductance DLTS measurement based on backgating effect of FETs, three kind of traps, namely Cr, HL4 and HL8, are identified for the substrate prepared by Horizontal Bridgman method. Also three kind of traps, namely EL2, HL4 and HL8, are identified for the non-doped Liquid Encapsulated Czochlalski (LEC) substrate. Simulation of the stationary characteristics of FETs is made at various temperature using a device model which includes both the depletion region at the n-i (channel-substrate) junction and influence of the deep traps. A model in which some other deep traps than EL2 are localized in the vicinity of n-i junction explains well the enhanced temperature dependence of saturation current. In addition to EL2, important contribution of hole traps to the FET characteristics is suggested for the devices prepared on the undoped LEC substrate by ion-implantation.