Yt. Ma et al., Characterization and modeling of threshold voltage shift due to quantum mechanical effects in pMOSFET, SOL ST ELEC, 44(7), 2000, pp. 1335-1339
The threshold voltage shift due to quantum mechanical effects (QMEs) has su
bstantial influences on modern pMOSFET characteristics. Investigations of Q
MEs in a pMOSFET are classified into two approaches: full-band calculation
and effective mass approximation. In this paper, formulation of carrier dis
tribution in the pMOSFET inversion layer in the threshold region based on t
he effective mass approximation is presented, and a new method to calculate
the threshold voltage shift due to QMEs is developed. The results with the
effective mass approximation are compared with the full-band calculation a
nd show satisfactory coincidence. Based on the present model, the subband s
tructure of the hole inversion layer and the earlier distribution character
istics are investigated. The quantum mechanical and semi-classical two-dime
nsional density of states (2D DOS) are calculated and compared. The depende
nce of the threshold voltage shift due to QMEs on substrate doping concentr
ation is then analyzed from the DOS point of view. (C) 2000 Elsevier Scienc
e Ltd. All rights reserved.