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A Dual Material Double-Layer Gate Stack Junctionless
Transistor for Enhanced Analog Performance
Ratul Kumar Baruah and Roy P. Paily
Department of Electronics and Electrical Engineering
Indian Institute of Technology Guwahati, India
{r.baruah,roypaily}@iitg.ernet.in
Abstract.
In this paper, we present a simulation study of analog circuit
performance parameters of a dual material double-layer gate stack (high-
k/SiO
2
) (DM-DGS) symmetric double-gate junctionless transistor (DGJLT).
The characteristics are demonstrated and compared with dual material gate
(DMG) DGJLT and single material (conventional) gate (SMG) DGJLT. DMG
DGJLT present superior transconductance (G
m
), early voltage (V
EA
) and
intrinsic gain (G
m
R
O
) compared to SMG DGJLT. These parameters are further
improved for DM-DGS DGJLT and it can be attributed to their better gate
control on the channel region.
Keywords:
Double-gate junctionless transistor (DGJLT), dual material double-
layer gate stack (DM-DGS), intrinsic gain, unity gain frequency, workfunction.
1
Introduction
The nano scale conventional metal-oxide semiconductor field-effect transistors
(MOSFETs) impose challenges such as enlarged gate leakage and added serious short
channel effects (SCEs), with the continuous miniaturization of device sizes. Multiple
gate FETs (Mug-FETs) have better scalability due to its superior controllability of the
gates on the channel region. However, very abrupt source and drain junctions
requirement put challenges in doping profile techniques and thermal budget.
Junctionless transistor (JLT), which does not have pn junction in the source-channel-
drain path has better short-channel effects (SCE) performance and therefore better
scalability, greatly simplified process flow and low thermal budgets after gate
formation [1]-[4]. However, JLTs suffer from lesser drain current and
transconductance compared to inversion mode MOSFETs due to high doping
concentration in the channel region [1],[5]-[6].
Dual-material gate (DMG) devices offer improved carrier transport efficiency,
transconductance and the drain output resistance than conventional MOSFETs [7]-
[14]. By adjusting the metal work functions, channel potential and electric field
distributions along the channel can be controlled. Razavi
et. al.
have reported that a
dual material gate stack, double-gate conventional MOSFET reduces the impact of
hot carrier effect and threshold voltage roll-off [8]. Long
et. al.
had experimentally
shown that DMG MOSFET offers simultaneous improvement of SCE as well as
