Negative magnetoresistance of polycrystalline thin Bi1−xSbx alloy films in quantizing magnetic fields

Abstract

We have investigated the magnetoresistance of thin polycrystalline semiconductor Bi1−xSbx films prepared on a flat fibreglass substrate at a temperature of 77 K using pulsed magnetic fields up to 50 T. For these investigations we used films exposed to different thermal annealing and having different grain structures. Negative magnetoresistance was obtained in semiconductor polycrystalline thin films affected by longitudinal magnetic fields to fields in excess of 20 T. This phenomenon has been qualitatively explained in terms of microcrystallites, which are energy band structure changes induced by strong magnetic fields. It is shown that, by measuring the magnetoresistance in strong and quantizing magnetic fields, we can determine the composition and quality of thin Bi–Sb films.