考虑量子效应的超薄体双栅肖特基源漏MOSFET电流解析模型

推导了超薄体双栅肖特基势垒MOSFET器件的漏电流模型,模型中考虑了势垒高度变化和载流子束缚效应.利用三角势垒近似求解薛定谔方程,得到的载流子密度和空间电荷密度一起用来得到量子束缚效应.由于量子束缚效应的存在,第一个子带高于导带底,这等效于禁带变宽.因此源漏端的势垒高度提高,载流子密度降低,漏电流降低.以前的模型仅考虑由于镜像力导致的肖特基势垒降低,因而不能准确表示漏电流.包含量子束缚效应的漏电流模型克服了这些缺陷.结果表明,较小的非负肖特基势垒,甚至零势垒高度,也存在隧穿电流.二维器件模拟器Silvaco得到的结果和模型结果吻合得很好.

An Analytical Model of Drain Current for Ultra-Thin Body and Double-Gate Schottky Source/Drain MOSFETs Accounting for Quantum Effects

A compact drain current including the variation of barrier heights and carrier quantization in ultrathin-body anddouble-gate Schottky barrier MOSFETs (UTBDG SBFETs) is developed. In this model, Schrodinger's equation is solved u-sing the triangular potential well approximation. The carrier density thus obtained is included in the space charge density toobtain quantum carrier confinement effects in the modeling of thin-body devices. Due to the quantum effects, the first sub-band is higher than the conduction band edge, which is equivalent to the band gap widening. Thus, the barrier heights atthe source and drain increase and the carrier concentration decreases as the drain current decreases. The drawback of theexisting models, which cannot present an accurate prediction of the drain current because they mainly consider the effectsof Schottky barrier lowering (SBL) due to image forces,is eliminated. Our research results suggest that for small nonnega-tire Schottky barrier (SB) heights,even for zero barrier height,the tunneling current also plays a role in the total on-statecurrents. Verification of the present model was carried out by the device numerical simulator-Silvaco and showed goodagreement.