From Figure $5\mathrm{.}12,$ calculate the activation energy for the diffusion of

$($a$)$ copper in silicon, and

$($b$)$ aluminum in silicon

$($c$)$ How do these values compare?

Temnaration $rNI$

$($Imes$)$ for the dirfusion of copper, gold, silver, and alu$-$

minum in silicon. Also noted are $D$ values at $500C.$