Characterization of Hall Factor with Seebeck Coefficient Measurement

The density-of-states effective mass (m(d)*) is commonly obtained by fitting the equation, S = (8 pi(2)k(B)(2)/3eh(2))m(d)*T(pi/3n)(2/3) (S, T, and n are the Seebeck coefficient, temperature, and the carrier concentration, respectively), to n-dependent S measurement. However, n is not a measurable parameter. It needs to be converted from the measured Hall carrier concentration (n(H)) using the Hall factor (r(H) = n/n(H)). The r(H) of material can be estimated by Single Parabolic Band (SPB) model if the band that contributed to transport is approximated to be parabolic and acoustic phonons dominantly scatter its carriers. However, the measurable n(H) is often used instead of n when utilizing the above equation due to the complex Fermi integrals involved in the SPB model calculation. Consequently, the m(d)* estimated from the above equation while using n(H) would be inaccurate. We propose the equation r(H) = 1.17 - [0.216 / {1 + exp((vertical bar S vertical bar - 101) / 67.1)}] as a simple and accurate method to obtain the r(H) from the measured S to facilitate the conversion from n(H) to n and eventually increase the accuracy of m(d)* estimated from the above equation.