We plan on using thermal evaporation chamber to grow a metal alloy $($thin film$)$ with

$Cu2\mathrm{.}0wt\%($weight percent$)$ and $Al98\mathrm{.}0wt\%.$ Source temperature is controlled at

$1350K.$ Please estimate what the target concentrations $($weight percent$)$ are in order to

maintain the right alloy composition. $($Vapor pressure for $Al$ at $1350K$ is ${10}^{-3}$ torr, and

for $Cu$ at $1350K$ is $2{10}^{-4}$ torr. Note that if we change the source temperature for growing

this alloy, the target concentration needs an adjustment based on their vapor pressure

variations.$)$