ZN DIFFUSION MECHANISM IN N-GAAS/ZN-ALGAAS/SE-ALGAAS STRUCTURES

Zn diffusion has been investigated in n-GaAs/Zn-AlGaAs/Se-AlGaAs structures during growth of n-GaAs layers. Se and Si are used as dopants for the n-GaAs layer. Zn diffusion in these structures depends strongly on the kind of dopant as well as on the carrier concentration in the n-GaAs layer. The amount of Zn diffused into both n-GaAs and Se-AlGaAs layers is much smaller for the Si-doped GaAs layer than for the Se-doped one. The slower Zn diffusion during the growth of Si-doped GaAs layers in these structures is reasonably interpreted by modifying the model that interstitial Ga diffused from the n-GaAs layer into the Zn-AlGaAs layer kicks substitutional Zn out. The density of interstitial Ga in the Si-doped GaAs layer could be lower than in the Se-doped GaAs, because the interstitial Ga atoms replace Si occupying the column III site, while this is not the case for Se-doped GaAs where Se occupies the column V site.