GATE EC 1996 Set 1 Q2.7 — BJT and MOSFET Amplifiers

A silicon $n$ $\text{MOSFET}$ has a threshold voltage of $1$ $\mathrm{V}$ and oxide thickness of $\mathrm{AO}$.

$\left[\varepsilon_{r}\left(\mathrm{siO}_{2}\right)=3.9, \varepsilon_{\mathrm{o}}=8.854 \times 10^{-14} \mathrm{~F} / \mathrm{cm}\right.$, $\left.q=1.6 \times 10^{-19} \mathrm{C}\right]$

The region under the gate is ion-implanted for threshold voltage tailoring. The dose and type of the implant (assumed to be a sheet charge at the interface) required to shift the threshold voltage to $-1 \mathrm{~V}$ are