Bikowski, A.; Ellmer, K.: Analytical model of electron transport in polycrystalline, degenerately doped ZnO films. Journal of Applied Physics 116 (2014), p. 143704/1-11
An analytical description of the charge carrier transport, valid for non-degenerated and degenerated semiconductors, was developed, critically reviewed, and fitted to the temperature-dependent Hall mobility data of magnetron sputtered, degenerately doped ZnO:Al films. Our extended model for grain boundary scattering in semiconductors of arbitrary degeneracy is based on previous models from literature and suitable to describe the Hall mobility of the carriers as a function of the free carrier concentration and the temperature at the same time. It is mathematically simple enough for a fast fit procedure, which is not possible with most of the previous models. Applying a combined transport model consisting of ionized impurity scattering, phonon scattering, and grain boundary scattering in degenerate semiconductors, we were able to determine the trap density at the grain boundaries Nt approx. 3*10^13 to 5*10^13 cm^-2 and the deformation potential Eac in the range of 5 eV to 9 eV depending on the details of the transport model.