Temperature dependent intrinsic carrier mobility and carrier concentration in individual ZnO nanowire with metal contacts

We studied the temperature-dependent electrical transport properties of individual ZnO nanowires with metal contacts. We used temperature dependent gate response curves to obtain the carrier mobility and the carrier concentration of ZnO nanowires as function of temperature; these were estimated from the modified transconductance equation to subtract the unavoidable contact resistance effect. As the temperature was lowered from 300 K, the carrier concentration decreased and the carrier mobility increased until it reached a maximum at 150 K. An increase in the carrier mobility upon cooling occurred due to a decrease in the electron-phonon scattering rate; the scatterings from defects and impurities became dominant at temperatures below 150 K. The intrinsic conduction of the ZnO nanowire itself, neglecting the contact effect, followed the thermal activation process related to zinc interstitials, Zn_I, rather than a variable range hopping behavior.