Properties of tellurium-doped epitaxial bismuth films

We report on the magnetoresistivity and Hall resistivity of epitaxial bismuth films grown by molecular-beam epitaxy (MBE) and doped n type with tellurium. We demonstrate that Te is a monovalent donor, up to a density of 5×{}10²⁵ m^-3 (5×{}10¹⁹ cm^-3). This can be explained by assuming that the Te-donor level is 190 meV above the L-point conduction-band edge. The extrinsic carrier density decreases with increasing temperature. The average electron mobility in the trigonal plane as a function of electron density is of the same order of magnitude as that of similarly doped indium antimonide. Electrons in bismuth are less sensitive to ionized impurity scattering than in group III-V compounds because of the high dielectric constant of the host. We also discuss the diffusion of tellurium in MBE-grown bismuth films.