Mobility analysis of highly conducting thin films: Application to ZnO

摘要

Hall-effect measurements have been performed on a series of highly conductive thin films of Ga-doped ZnO grown by pulsed laser deposition and annealed in a forming-gas atmosphere (5% H_2 in Ar). The mobility as a function of thickness d is analyzed by a simple formula involving only ionized-impurity and boundary scattering and having a single fitting parameter, the acceptor/donor concentration ratio K=N_A/N_D. For samples with d=3-100 nm, K_(avg)=0.41, giving N_D=4.7 × 10~(20) and N_A = 1.9 × 10~(20) cm~(-3). Thicker samples require a two-layer formulation due to inhomogeneous annealing.