STUDIES ON THE HOLES OF P-TYPE BI2TE2.85SE0.15 SINGLE-CRYSTAL

A single crystal of p-type Bi2Te2.85Se0.15 was grown by the Bridgman technique. Components of the resistivity, Hall coefficient and magnetoresistivity tensors were measured over the temperature range from 77 to 300 K and the results analyzed with the six-valley model. The scattering parameter rp and the reduced Fermi energy ηp of the holes were computed through the measurements of the components of the thermoelectric power tensor and the numerical analysis of the Fermi-Dirac integral with an arbitrary real index. The rp-values are -0.64 and -0.65 at 90 and 300 K, respectively, and it is found that rp differs from - 1 2 which corresponds to carrier scattering by the acoustic phonons. The hole density has a constant value of 5.3 × 1024 m-3 over the temperature range from 90 to 140 K. It increases, however, with increasing temperature above 140 K and has a value of 5.8 × 1024 m-3 at 300 K. The mobility ratio has a temperature dependence represented by T0.26. The energy gap was determined to be 0.18 eV from the components of the resistivity and Hall tensors in the intrinsic region. © 1990.