Role of Neutral Impurity Scattering in the Analysis of Hall Data from ZnO and Other II-VI Materials

Abstract

AbstractTo determine donor and acceptor concentrations affecting electrical properties in ZnO crystals, the relaxation time approximation (RTA) has been used to analyze mobility and carrier concentration data measured from 80 to 400 K. Five scattering mechanisms are included: polar-optical-phonon, piezoelectric potential, deformation potential, ionized impurity, and neutral impurity scattering. Temperature dependences of intrinsic mobilities and Hall r factors are determined. Neutral impurity (ni) scattering can play an important role in limiting the total mobility in ZnO single crystals. By including ni scattering, the experimental deformation potential E1 = 3.8 eV for ZnO can be used, rather than treating E1 as a fitting parameter. This approach yields “intrinsic” mobilities for n-type and p-type ZnO, and other II-VI materials. At 300 K, the intrinsic electron Hall mobility in ZnO is predicted to be 230 cm2/Vs. The results of fitting the temperature dependences of mobility and carrier concentrations from representative ZnO and CdSe bulk samples are shown. Intrinsic results for n-type CdS and ZnS will also be discussed. The 300-K intrinsic hole Hall mobility in ZnO is predicted to be about 50 cm2/Vs.