Strong temperature dependence of the Hall factor of p-type CoSb3: A re-analysis incorporating band nonparabolicity

Abstract

The Hall factor has been calculated as a function of temperature for p-type CoSb3 samples reported by Hui et al. [J. Appl. Phys. 115, 103704 (2014)] in addition to those reported by Caillat et al. [J. Appl. Phys. 80, 4442 (1996)], incorporating the valence band nonparabolicity. For the nominally undoped p-type samples, reported by Caillat et al., the Hall factor was calculated to increase with temperature from about 1.6 around room temperature to about as large as 5 at 900K. Owing to the incorporation of the Hall factor, the net acceptor concentration has been corrected to be larger by about 1.6 times. Furthermore, due to the strong temperature dependence of the Hall factor, the band-gap energy deduced through fitting the temperature dependence of the Hall coefficient has been corrected to be smaller by about 0.03eV than the values deduced when assuming a constant Hall factor of unity. It has also been shown that, even when the temperature dependence of the Hall factor is considered, the incorporation of the second valence band into the calculation is necessary to explain the anomalous increase of the Hall coefficient with temperature in the Sn-doped p-type CoSb3 sample reported by Hui et al.