tesi R. Miscioscia.pdf - EleA@UniSA

Chapter 1 19
The formula in eq. 18 gives the static characteristics of the device in
the accumulation mode when VGS+V0≤VDS. Differently from the
standard MOSFET equation [3] in the active region, there’s an
injection-dependant contribution (see eq. 18 and eq. 19).
1 W
I DSinj = μ nε
cht
ch ΔE
2 L
eq. 19 ( ) 2
Such contribution (see eq. 19) takes into account the space-charge
limited current near the drain electrode becomes relevant at high drain
fields, for short channels and for relatively thick semiconductor layers
and can explain some deviations from the standard model such as the
lack of a saturation behavior for higher source-drain voltages.
The lack of saturation in the channel current can be observed
after Koehler-Biaggio works [1] by adopting the same formalism
utilized to model charge injection in insulators in the Gurney-Mott
approach. Non-saturation effects are more pronounced at low gate
voltages and ad it has been shown in figure 3.
figure 3: non-saturating behaviour of channel current due to the contribution of the injection at
S/D electrodes as shown by Koehler-Biaggio in [1].
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