Electrical Properties and Magnetoresistance of Nanogranular SnO₂Films

Abstract

Magnetotransport properties of the nanogranular SnO 2 films were invesigated. Non-linear current-voltage (I−V ) characteristics were observed at low temperatures. The temperature dependence of the resistance and non-ohmic I−V curves can be well approximated by fluctuation-induced tunnelling model, indicating importance of the contacts barriers between SnO2 grains. Magnetoresistance was measured within temperature range 2-15.3 K and could be consistent with the variable-range hopping conduction mechanism due to existence of localized states on the surface of SnO2 grains.

Origin of negative magnetoresistance in polycrystalline SnO2films

“…It is known that both doping 12,15,17,18 and disorder 7,15 can significantly change the conductivity. Different charge transport mechanisms, varying from activation 10,19 and hopping 10,11,20,21 conductivity to tunneling 7,10,22 and diffusive transport 23,24 were reported for thin SnO 2 films. The origins of charge carriers in unintentionally doped SnO 2 structures are associated with oxygen vacancies 25 and shallow donors from tin interstitials 26 or with inevitable contaminations (namely with hydrogen).…”

Weak Localization in Polycrystalline Tin Dioxide Films

“…For example, doping of SnO 2 by Cu, Al and In induces a decrease of intrinsic n-type conductivity as a result of the compensation effect [19]. Depending on the crystalline structure and the dopants concentration, different charge transport mechanisms can dominate in SnO 2 films: hopping conductivity [20][21][22], thermal activation [23], tunneling through the grain boundaries [24,25]. Quantum corrections to the conductivity due to weak localization (WL) and electron-electron interaction effects (EEI) can be observed in highly doped tin dioxide films at low temperatures [15,[26][27][28][29].…”