Structural defects in tin-doped antimony telluride single crystals

The structural perfection and homogeneity of Czochralski-grown Sb2Te3 and Sb1.96Sn0.4Te3 crystals were characterized by transmission electron microscopy and electron probe x-ray microanalysis. The Sb, Sn, and Te core-level and valence-band x-ray photoelectron spectra were measured, and the corresponding binding energies were determined. The effect of Sn doping on the electronic structure and transport properties of the crystals was examined. The crystals were shown to be uniform in Sb : Te ratio and to have a relatively perfect structure. The dislocation density in the crystals was determined by electron microscopy and selective etching. The origin of the morie patterns observed in electron micrographs was discussed. Sn doping of Sb2Te3 was shown to produce no significant shifts of the core levels or changes in the electronic density of states in the valence band.