A subthreshold surface potential model for short-channel MOSFET taking into account the varying depth of channel depletion layer due to source and drain junctions

A Subthreshold Surface Potential and Drain Current Model for Lateral Asymmetric Channel (LAC) MOSFETs

“…With reference to Fig 1, the following equation can be derived by applying Gauss's law and neglecting mobile charge carriers to a rectangular Gaussian box in the channel depletion region [15,16] J2ll' To predict IJis accurately, an appropriate model for Yd (x) has to be used in (1). If the effect of the source and drain junction depletion regions is neglected, it may be expressed as Ysx = { 2f,.…”

“…A good model should not only have a physically based approximate and simple description for it but this should give an analytical solution of ( 1) also. Keeping these requirements in mind and also considering the typical variation of Yix) with x, we model this by YJx) =(ax+ h) 2 as in [15] for the portion of the channel upto which the source/drain junction depletion region penetrates the channel horizontally, with the end values given by and Yc~(O) = xj + X,, and Yc~(L) =X;+ X,c~· Where Xj is the junction depth, X,, and X," are the vertical penetrations of the depletion layer around the source and drain junctions respectively. For LAC devices, the horizontal penetration x,, at the source end due to the built-in potential V"; and V 58 may be expressed as x,, = In general, as YJx) is concerned, the channel may be divided into four regions with known values at the two ends.…”

“…Moreover, the effective conduction layer thickness of the channel also needs correction for deep submicrometer devices because of a similar reason. Recently we have proposed a subthreshold surface potential model for conventional MOSFETs in which the effects of the channel depletion layers due to source and drain junction have been taken into account [15].…”

Analog and RF performance investigation of cylindrical surrounding-gate MOSFET with an analytical pseudo-2D model

“…A pseudo-2-D analysis is used as a compromise that produces a simpler and manageable one-dimensional analytical expression, retaining the accuracy of two-dimensional analysis. Such works for short channel SRG MOSFET and uniformly doped channel/pocket implanted devices have been already reported [25,26]. The quantum-mechanical-effects (QME) start to become significant in the devices with silicon film thickness smaller than 10 nm [18,27].…”

Modified analytical model for subthreshold current in short channel MOSFET's

“…In subthreshold regime devices have significantly higher gain because of the higher transconductanceto-current ratio [4]; thus the model would be important for designing of analog circuits too. Therefore, a simple and accurate analytical model is needed for hand estimation of circuit characteristics.…”