The scattering mechanism analysis of anisotropic (00l)-orientation bismuth films based on magnetoresistance measurement method

Abstract

The magnetoresistance anisotropic effect of (00l)-oriented semimetal polycrystalline bismuth (Bi) films is proposed as a candidate for Ettingshausen device and magnetoresistance device. By tuning film samples, 29 nm thickness (00l)-oriented columnar bismuth films with different grain sizes were prepared. The electrical transport measurement results showed that due to the different grain sizes, the magnetoresistance anisotropy of the Bi films with the same thicknesses differed by 3 times at low temperatures (T = 2 K). The main collision mechanism controlling the Bi film resistance was discriminated by whether the surface scattering or grain boundary scattering, based upon whether the magnetoresistance depends on the thickness or the grain sizes. The analysis result indicated that the surface scattering of the Bi film directly affected the semimetal to semiconductor transition. The present study provides a pathway for the electronic device application operating at low temperature by controlling the grain sizes.