$44$ Indium atoms are to be diffused into a silicon

wafer using both predeposition and drive$-$in heat

treatments; the background concentration of In

in this silicon material is known to be $2{10}^{20}$

atoms $\frac{?}{m^3}.$ The drive$-$in diffusion treatment is to be

carried out at $1175C$ for a period of $2\mathrm{.}0$ h $,$ which

gives a junction depth $x_j$ of $2\mathrm{.}35.m.$ Compule

the predeposition diffusion time at $925C$ if the

surface concentration is maintained at a constant

level of $2\mathrm{.}5{10}^{2h}$atom$\frac{s}{m^3}.$ For the diffusion of

In in Si$,$ values of $Q_A$ and $O_0$ are $3\mathrm{.}63e\frac{V}{a}$tom and

$7\mathrm{.}85{10}^5\frac{m^7}{s},$ respectively.