Abstract:
A new model based on linear depletion inside the channel region has been proposed
for long channel Junctionless Double Gate (JL DG) MOSFETs. The proposed model
shows improved performance over the previous models based on abrupt depletion.
This new model provides a different way to determine surface potential of JL DG
MOSFETs. The model based on gradual depletion provides different sets of equations
for surface potential which are valid for different regions of operations. Thus
there is a trade-off between accuracy and complexity in using the proposed model.
Having the knowledge of surface potential, the proposed model obtains expressions
for current and threshold voltage. The current expressions have been evaluated
using numerical techniques. Surface potential characteristics and current voltage
characteristics are found to have smooth transition between fully depleted region
and partially depleted region. This smoothness may prove useful for SPICE like
programs. Capacitance-voltage characteristics, output conductance and transconductance
characteristics have also been observed, analyzed and compared against the
results obtained from TCAD simulations. Upon comparison, it has been found that
the results obtained from proposed model matches quite perfectly with the results
provided by TCAD tool. Finally the effects of different device and process parameters
on threshold voltage of the JL DG device and the sensitivities of threshold
voltage on these parameters have been explored and analyzed. It has been observed
that threshold voltage of JL DG MOSFET is very sensitive to parameter variations
which would require proper control of geometry and impurity concentration.
