Two-band analysis of hole mobility and Hall factor for heavily carbon-doped p-type GaAs

Abstract

We solve a pair of Boltzmann transport equations based on an interacting two-isotropic-band model in a general way first to get transport parameters corresponding to the relaxation time. We present a simple method to calculate effective relaxation times, separately for each band, which compensate for the inherent deficiencies in using the relaxation time concept for polar optical-phonon scattering. Formulas for calculating momentum relaxation times in the two-band model are presented for all the major scattering mechanisms of p-type GaAs for simple, practical mobility calculations. In the newly proposed theoretical framework, first-principles calculations for the Hall mobility and Hall factor of p-type GaAs at room temperature are carried out with no adjustable parameters in order to obtain direct comparisons between the theory and recently available experimental results. In the calculations, the light-hole-band nonparabolicity is taken into account on the average by the use of energy-dependent effective mass obtained from the k-p method and valence-band anisotropy is taken partly into account by the use the Wiley's overlap function.. The calculated Hall mobilities show a good agreement with our experimental data for carbon-doped p-GaAs samples in the range of degenerate hole densities. The calculated Hall factors show r H ϭ1.25-1.75 over hole densities of 2ϫ10 17 -1ϫ10 20 cm Ϫ3 .

A computational assessment of the electronic, thermoelectric, and defect properties of bournonite (CuPbSbS3) and related substitutions

“…AMSET also models inter-band scattering of the heavy and the light band, which is known to reduce the electrical mobility. 51,52 A disadvantage of AMSET is that it currently uses a one-dimensional model of the averaged band structure for a single pocket, which cannot capture anisotropy and may be less accurate for multivalley compounds. Previous work indicates that, compared with BoltzTrap, AMSET offers more accurate prediction of mobility and almost identical or slightly better accuracy in predicting the Seebeck coefficient.…”

Infrared studies of hole-plasmon excitations in heavily-doped p-type MBE-grown GaAs:C

“…For ionizedimpurity scattering ͓which is the dominant room-temperature scattering mechanism in heavily-doped GaAs:C ͑Refs. 44 and 49͒, his analysis shows that the standard IR-analysis approximation can yield a best-fit that differs from the true value of ͗͘ by nearly a factor of 2 for low ͑nondegenerate͒ doping. But with increased doping, the error decreases, and Lyden's work shows the error to be entirely negligible for highly degenerate samples (Ͼ4).…”

On Hall scattering factors for holes in GaAs

“…9 Values of r p determined in most of the calculations are significantly larger than unity, ranging from 1.25 to greater than 2. 4,6,8,10,11 Such large r p 's, if accurate, can lead to significant error in determining p from a Hall-effect measurement, since most workers simply assume rϭ1 for holes, as they do for electrons.…”

“…Although the individual band Hall factors, r pl and r ph , respectively, are also in the range 1.0-1.2 ͑if the bands are noninteracting͒, the combined Hall factor can be much larger. 4 A few calculations have included much ͑although not all͒ of the necessary complexity of hole transport in GaAs; [4][5][6][7][8] Wiley has given an excellent discussion of the various problems involved. 9 Values of r p determined in most of the calculations are significantly larger than unity, ranging from 1.25 to greater than 2.…”