Hole Scattering in GaSb: Scattering on Space Charge Regions Versus Dipole Scattering

Abstract

Hole concentration and mobility were investigated by Hall measurements in nominally undoped p-type GaSb in the temperature range from 77 to 300 K. The dependence of the thermal ionization energy of native acceptors on the acceptor centre concentration and on the compensation degree was determined. The temperature dependence of the hole mobility was analyzed using a heuristic semi-empirical model as well as using a phenomenological two-hole band model. Space charge scattering and/or dipole scattering described with a mobility contribution with a ∼ T −1/2 like temperature dependence dominated the hole mobility in the investigated temperature range.

Hole mobility in InP and GaSb

“…Van der Pauw Hall data were measured between 300 K and 77 K on 18 samples of undoped p-type bulk grown GaSb obtained from three different sources [3,4] as well as on samples of InP:Zn bulk crystals obtained from two different sources [5]. The room temperature hole concentration of the GaSb samples studied was in the range from 6x10 16 cm -3 to 1x10 18 cm -3 , the corresponding Hall mobility was between 420 cm 2 /Vs and 660 cm 2 /Vs at 300 K and between 400 cm 2 /Vs and 2300 cm 2 /Vs at 77 K. The room temperature hole concentration of the InP samples studied was in the range from 2x10 17 cm -3 to 5x10 18 cm -3 , the corresponding Hall mobility was between 45 cm 2 /Vs and 100 cm 2 /Vs.…”

“…From this analysis the acceptor and donor concentrations which are the relevant input parameters in the mobility analysis, were deduced [4,5]. It was found that all samples measured were characterized by a substantial compensation degree, K > 0.5.…”

“…In the literature are used. Besides lattice scattering (with n i = -1.5 and μ L (300) = 900 cm 2 /Vs for GaSb [4,6,7], and n i = -2.2 and μ L (300) = 150 cm 2 /Vs for InP [6,8] deduced from empirical data from the literature) and ionized impurity scattering (n i =3/2), the inclusion of an additional scattering mechanism characterized with n i = -1/2 was found necessary for the fits. This latter scattering mechanism Is usually ascribed to carrier scattering on space charge regions [9,10], but other physical mechanism could also play a role.…”

“…Because of the high compensation degree in most of the samples the effectiveness of the Coulomb scattering by single impurities is much reduced due to correlation between the positions of the scattering centres, and is converted to much less effective space charge region and dipole scattering, both described by n i = -1/2. Considering only space charges, the fitted values of the product of the scattering cross section and of the density of space charge regions are QN SC = (1 -1.5)x10 5 cm -1 for GaSb [4] and QN SC = (4 -7)x10 5 cm -1 for InP.…”