Electrical and thermoelectric properties of ZnO under atmospheric and hydrostatic pressure

Temperature (for T = 77-400 K) and pressure (for P <= 8 GPa) dependences of conductivity sigma(T,P). Hall coefficient R-H(T, P), and Seebeck coefficient Q(T) were studied in single-crystal n-ZnO samples with the impurity concentration N-i = 10(17) - 10(18) cm(-3) and free-electron concentration n = 10(13)-10(17) cm(-3). Single crystals were grown by the hydrothermal method. Dependence of the ionization energy of a shallow donor level on the impurity concentration E-d1(N-d) is determined, along with the pressure coefficients for the ionization energy E-d1/partial derivative P and static dielectric constant partial derivative chi/partial derivative P. A deep defect level with the energy E-d2 = 0.3 eV below the bottom of the conduction band is found. The electron effective mass is calculated from the obtained data on the kinetic coefficients R-H(T) and Q(T).