Transmuted-Center Fermi-Level Spectroscopy in Slow-Neutron-Irradiated ZnO

Measurements of resistivity vs time and temperature between 70° and 300°K were made on an n-type ZnO crystal which had been irradiated in a slow neutron-integrated flux of 4.1×1020 cm−2. During the course of the measurements, the crystal was transmutation doped by the 245-day half-life decay of 65Zn to 65Cu. 69Ga was also present in the crystal, as the daughter of the shorter-lived 69Zn. The data were treated using a phenomenological theory of transmuted-center Fermi-level spectroscopy (TCFLS) based upon assumptions of sample homogeneity, electron-system equilibrium, filled transmuted acceptors, and linear relation at constant temperature between Fermi level and log10 resistivity. The data are consistent with a 69Ga-donor model, two levels of which are resolved by the TCFLS technique. The results illustrate the potentiality of TCFLS for determination of semiconductor forbidden-band state parameters, and also for carrier microscopic-mobility determination. Two model parameters, corresponding to the concentrations of the shallow forbidden-band states, were determined to within 3% standard error.