Antisite defects of Bi2Te3 thin films

We have successfully grown Bi2Te3 thin films on CdTe(111)B using molecular- beam epitaxy. Structural and transport properties have been investigated us ing in situ reflection high-energy electron diffraction, theta-2 theta x-ra y diffraction analysis, thermopower, and Hall measurements. Both the crysta llinity and the transport are found to be strongly affected by nonstoichiom etry. The most stoichiometric sample had a high crystallinity, high thermop ower, and high electron mobility. However, Bi2Te3 films with excess Te had a reduced lattice constant, poorer crystallinity, reduced magnitude of the thermopower, and reduced mobility. All of these observations can be explain ed in terms of antisite defects in which excess Te occupies Bi lattice site s and behaves as a n-type dopant. (C) 1999 American Institute of Physics. [ S0003-6951(99)04136-4].