Experiments have shown that scanning photoelectron microscopy can provide direct evidence for differential oxidation of step edge defects relative to basal planes of Bi2Te2Se. Single crystals of Bi2Te2Se, Bi2Te3, and Bi2 Se3 were grown from a melted mixture of the elements and were cleaved from the large boules thus prepared. Members of the Bi2Te2Se3 family have a layered structure consisting of quintuple layers of Te/Se (1) - Bi - Te/Se (2) - Bi - Te/Se (1). These layers are separated by a van der Waals gap, which allows in principle for facile cleavage along a basal plane leading to a terraced surface that can be visualized by atomic force microscopy (AFM). Removal of the uppermost layer of a cleaved sample is accomplished by applying adhesive tape to the surface and lifting off a thin sheet of Bi2(Te,Se)3 to expose a pristine surface. Surface oxidation was followed by calculating the ratio of peak areas of oxidized and unoxidized species for each element. The extremely high photon flux of the focused X-ray beam relative to that of a standard spectrometer causes a partial and/or full reduction of the surface oxide, which has been observed for other metal oxides studied by this technique.
All Science Journal Classification (ASJC) codes
- Chemical Engineering(all)
- Materials Chemistry