$5)$ Tutorial # $10$ Date: $04/11/241.$ For a n$-$channel GaAs MESFET, the Schottky barrier height is $0\mathrm{.}85$ V and semiconductor donor doping density is $1016$ cm$-3.$ Given that electron mobility is $6000$ cm$2/$V$-$s$,$ channel width $($Z$)$ and length $($L$)$ are $25$ m and $1\mathrm{.}0$ m respectively, channel depth $($a$)$ is $0\mathrm{.}5$ m$.$ Assume that effective density of states in the conduction band is $5\mathrm{.}0$ x $1017$ cm$-3$ and GaAs permittivity is $13\mathrm{.}2$ o$.$Answer the following:$($iv$)$ VD $($sat$)$ for gate bias of VGS $=-1\mathrm{.}5$ V$.($v$)$ If channel depth reduced to $0\mathrm{.}25$ m $($from $0\mathrm{.}5$ m$),$ will it be a normally ONor normally OFF device? Justify your answer$\mathrm{.}2.$ An n$-$channel GaAs MESFET operating at $300$ K is developed by forming one schottkycontact and two ohmic contacts. Suppose the Schottky barrier height at gate contact is $0\mathrm{.}91$V and GaAs is doped with donors of $2\mathrm{.}3$ x $1015$ cm$-3$ concentration. Design the metallurgical $($i$)$ Calculate the potential barrier from GaAs to metal.$($ii$)$ Is it a depletion mode or enhancement mode device? Justify your answer withproper data.$($iii$)$ Calculate the threshold voltage $($VT$)$