To study the nature of metal-semiconductor junction, metal-clad InAs quantum wells with aluminum deposited on 15-nm thick InAs grown on (100) GaAs with AlSb barrier were prepared by an in-situ method (aluminum was grown immediately by molecular beam epitaxy) and by an ex-situ method (aluminum was deposited after exposing InAs surface in ambient condition by selective etching). Cross sectional TEM studies indicated that the Al grains in the clad aluminum layer were randomly arranged in the ex-situ grown junctions, while, in the in-situ samples, the aluminum grains were found to be well oriented to the underlying InAs.

When the interface is viewed along [Oil], three observed crystallographic relationships for in-situ Al growth are

1. 1. [011]AI // [011]InAs and (100)AI // (100)InAs as shown in Fig. 1(a): the aluminum grains of facecentered cubic (fee) structure are perfectly aligned with the fee InAs lattice when they grow;