A Closed-Form Model for Position-Dependent Potential across the Channel in DG-MOSFETs

A closed-form model for electrostatic potential distribution in the direction normal to the channel for double-gate （DG） MOSFETs is presented. The effects of doping （NA for nMOS） and minority carriers both are taken into account for the first time, in solving Poisson＇s equation analytically. Excellent agreement between model-predicted results and numerical device simulation is achieved for a wide range of body thickness, light or high channeldoping, under various bias conditions. This complete closed form for position-dependent potential distribution has wide applications for MOS compact modelling and device design.     

Spin Injection from Ferromagnetic Metal Directly into Non-Magnetic Semiconductor under Different Injection Currents

For ferromagnetic metal （FM）/semiconductor （SO） structure with ohmic contact, the effect of carrier polarization in the semiconductor combined with drift part of injection current on current polarization is investigated. Based on the general model we established here, spin injection efficiency under different injection current levels is calculated. Under a reasonable high injection current, current polarization in the semiconductor is actually much larger than that predicted by the conductivity mismatch model because the effect of carrier polarization is enhanced by the increasing drift current. An appreciable current polarization of 1% could be achieved for the FM/SC structure via ohmic contact, which means that efficient spin injection from FM into SC via ohmic contact is possible. The reported dependence of current polarization on temperature is verified quantitatively. To achieve even larger spin injection efficiency, a gradient doping semiconductor is suggested to enhance the drift current effect.