109 research outputs found
Shielded Ohmic Contact (ShOC) Rectifier: A New Metal-Semiconductor Device with Excellent Forward and Reverse Characteristics
We report a new structure, called the Shielded Ohmic Contact (ShOC) rectifier
which utilizes trenches filled with a high barrier metal to shield an Ohmic
contact during the reverse bias. When the device is forward biased, the Ohmic
contact conducts with a low forward drop. However, when reverse biased, the
Ohmic contact is completely shielded by the high barrier Schottky contact
resulting in a low reverse leakage current. Two dimensional numerical
simulation is used to evaluate and explain the superior performance of the
proposed ShOC rectifier.Comment: http://web.iitd.ac.in/~mamidala
New Schottky-gate Bipolar Mode Field Effect Transistor (SBMFET): Design and Analysis using Two-dimensional Simulation
A new Schottky-gate Bipolar Mode Field Effect Transistor (SBMFET) is proposed
and verified by two-dimensional simulation. Unlike in the case of conventional
BMFET, which uses deep diffused p+-regions as the gate, the proposed device
uses the Schottky gate formed on the silicon planar surface for injecting
minority carriers into the drift region. The SBMFET is demonstrated to have
improved current gain, identical breakdown voltage and ON-voltage drop when
compared to the conventional BMFET. Since the fabrication of the SBMFET is much
simpler and obliterates the need for deep thermal diffusion of P+-gates, the
SBMFET is expected to be of great practical importance in medium-power
high-current switching applications.Comment: Journal Pape
Bipolar Charge Plasma Transistor: A Novel Three Terminal Device
A distinctive approach for forming a lateral Bipolar Charge Plasma Transistor
(BCPT) is explored using 2-D simulations. Different metal work-function
electrodes are used to induce n- and p-type charge plasma layers on undoped SOI
to form the emitter, base and collector regions of a lateral NPN transistor.
Electrical characteristics of the proposed device are simulated and compared
with that of a conventionally doped lateral bipolar junction transistor with
identical dimensions. Our simulation results demonstrate that the BCPT concept
will help us realize a superior bipolar transistor in terms of a high current
gain compared to a conventional BJT. This BCPT concept is suitable in
overcoming doping issues such as dopant activation and high-thermal budgets
which are serious issues in ultra thin SOI structures
New Silicon Carbide (SiC) Hetero-Junction Darlington Transistor
Basic SiC bipolar transistors have been studied in the past for their
applications where high power or high temperature operation is required.
However since the current gain in SiC bipolar transistors is very low and
therefore, a large base drive is required in high current applications.
Therefore, it is important to enhance the current gain of SiC bipolar
transistors. Using two dimensional mixed mode device and circuit simulation,
for the first time, we report a new Darlington transistor formed using two
polytypes 3C-SiC and 4H-SiC having a very high current gain as a result of the
heterojunction formation between the emitter and the base of transistor. The
reasons for the improved performance are analyzed.Comment: http://web.iitd.ac.in/~mamidala
Estimation and Compensation of Process Induced Variations in Nanoscale Tunnel Field Effect Transistors (TFETs) for Improved Reliability
Tunnel Field Effect Transistors (TFET) have extremely low leakage current,
exhibit excellent subthreshold swing and are less susceptible to short channel
effects. However, TFETs do face certain special challenges, particularly with
respect to the process induced variations in (i) the channel length and (ii)
the thickness of the silicon thin-film and the gate oxide. This paper, for the
first time, studies the impact of the above process variations on the
electrical characteristics of a Double Gate Tunnel Field Effect Transistor
(DGTFET). Using two dimensional device simulations, we propose the Strained
Double Gate Tunnel Field Effect Transistor (SDGTFET) with high-k gate
dielectric as a possible solution for effectively compensating the process
induced variations in the on-current, threshold voltage and subthreshold-swing
improving the reliability of the DGTFET.Comment: Journal Pape
Schottky Collector Bipolar Transistor without Impurity Doped Emitter and Base: Design and Performance
In this paper, we report an alternative approach of implementing a Schottky
collector bipolar transistor without doping the ultrathin SOI film. Using
different metal work function electrodes, the electrons and holes are induced
in an intrinsic silicon film to create the n emitter and the p base regions,
respectively. Using two-dimensional device simulation, the performance of the
proposed device has been evaluated. Our results demonstrate that the charge
plasma based bipolar transistor with Schottky collector exhibits a high current
gain and a better cut-off frequency compared to its conventional counterpart
Dielectric-Modulated Impact-Ionization MOS (DIMOS) Transistor as a Label-free Biosensor
In this letter, we propose a dielectric-modulated Impact-Ionization MOS
(DIMOS) transistor based sensor for application in label-free detection of
biomolecules. Numerous reports exist on the experimental demonstration of
nanogap-embedded FET-based biosensors, but an I-MOS based biosensor has not
been reported previously. The concept of a dielectric-modulated I-MOS based
biosensor is presented in this letter based on TCAD simulation study. The
results indicate a high sensitivity to the presence of biomolecules even at
small channel lengths. In addition, a low variability of the sensitivity to the
charges on the biomolecule is observed. The high sensitivity, dominance of
dielectric-modulation effects and operation at even small channel lengths makes
the DIMOS biosensor a promising alternative for CMOS-based sensor applications
Compact Analytical Model of Dual Material Gate Tunneling Field Effect Transistor using Interband Tunneling and Channel Transport
In this paper we have developed a two dimensional (2D) analytical model for
surface potential and drain current for a long channel Dual Material Gate (DMG)
Silicon-on-Insulator (SOI) Tunneling Field Effect Transistor (TFET). This model
includes the effect of drain voltage, gate metal work function, oxide thickness
and silicon film thickness, without assuming a fully depleted channel. The
proposed model also includes the effect of charge accumulation at the interface
of the two gates and the variation in the tunneling volume with the applied
gate voltage. The accuracy of the model is tested using two-dimensional
numerical simulations. In comparison to the conventional TFET, the proposed
model predicts that a DMGTFET provides a higher ON-state current (ION), a
better ON-state to OFF-state current (ION/IOFF) ratio and a better
sub-threshold slope (SS)
A New Strained-Silicon Channel Trench-gate Power MOSFET: Design and Analysis
In this paper, we propose a new trench power MOSFET with strained Si channel
that provides lower on resistance than the conventional trench MOSFET. Using a
20% Ge mole fraction in the Si1-xGex body with a compositionally graded
Si1-xGex buffer in the drift region enables us to create strain in the channel
along with graded strain in the accumulation region. As a result, the proposed
structure exhibits 40% enhancement in current drivability, 28% reduction in the
on-resistance and 72% improvement in peak transconductance at the cost of only
12% reduction in the breakdown voltage when compared to the conventional trench
gate MOSFET. Furthermore, the graded strained accumulation region supports the
confinement of carriers near the trench sidewalls improving the field
distribution in the mesa structure useful for a better damage immunity during
inductive switching.Comment: http://web.iitd.ac.in/~mamidal
A New High Voltage 4H-SiC Lateral Dual Sidewall Schottky (LDSS) Rectifier: Theoretical Investigation and Analysis
In this paper, we report a new 4H-SiC Lateral Dual Sidewall Schottky (LDSS)
rectifier on a highly doped drift layer consisting of a high-barrier sidewall
Schottky contact on top of the low-barrier Schottky contact. Using
two-dimensional device simulation, the performance of the proposed device has
been evaluated in detail by comparing its characteristics with those of the
compatible Lateral Conventional Schottky (LCS) and Lateral Trench Sidewall
Schottky (LTSS) rectifiers on 4H-SiC. From our simulation results, it is
observed that the proposed LDSS rectifier acts as a low-barrier LTSS rectifier
under forward bias conditions and as a high-barrier LTSS rectifier under
reverse bias conditions making it an ideal rectifier. The LDSS rectifier
exhibits an on/off current ratio (at 1 V / -500 V) of 5.5x10e7 for an epitaxial
layer doping of 1x10e17 /cm^3. Further, the proposed LDSS structure exhibits a
very sharp breakdown similar to that of a PiN diode in spite of using only
Schottky junctions in the structure. We have analyzed the reasons for the
improved performance of the LDSS.Comment: http://web.iitd.ac.in/~mamidala
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