Sn119Mössbauer study of shallow and deep states of Sn inGa1xAlxAs

Abstract
Epitaxial layers of Ga1x AlxAs (0≤x≤1) doped with enriched119 tin have been grown by metal-organic vapor-phase epitaxy and characterized by Sn119 Mössbauer spectroscopy and Hall measurements. The x=0 and x=1 samples yield Mössbauer spectra that are interpreted in terms of two Sn sites corresponding to substitutional shallow donors and clustered species, with the former site population clearly dominating. The x=0.3–0.4 samples yield significantly altered Mössbauer resonance with a new type of dominating site. This can be interpreted as due to the DX-center deep level with an electronic structure altered due to electron localization and a local distortion of cubic symmetry in accord with recent models.