Berlin 2012 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 7: Transport and Diffusion II
MM 7.4: Vortrag
Montag, 26. März 2012, 12:15–12:30, H 1029
Transport Properties of In2O3 and its surface electron accumulation layer — •Natalie Preissler, Oliver Bierwagen, and James. S. Speck — preissler@pdi-berlin.de
We used variable temperature Hall measurements and room temperature thermoelectric measurements to determine the transport properties (mobility, sheet resistance, charge density, Seebeck-coefficient) of In2O3 thin films and their surface electron accumulation layers (SEALs). SEALs have an important impact on device applications and were shown already by x-ray photoelectron spectroscopy (XPS) and current-voltage (I-V) measurements, while their actual transport properties are still unknown. The investigated In2O3 samples were about 500 nm thick and were grown on insulating Yttria-stabilized zirconia (YSZ) by plasma-assisted molecular beam epitaxy. Unintentionally doped (uid) In2O3 exhibits n-type conductivity with a significantly lower volume electron concentration than in the SEAL. Acceptor doping by Mg turned the bulk of the samples insulating to maximize the relative contribution of the SEAL to the total conductivity. As a result we can estimate the sheet resistance of the SEAL to be greater than 46 kΩ. Current-voltage measurements with Hg contacts showed the existance of the SEAL. Temperature dependent Hall measurements were used to differentiate between the degenerate SEAL (high volume electron concentration, no freeze-out) and non-degenerate bulk (low concentration, freeze-out). While Hall measurements give a total sheet electron concentration, the Seebeck coefficient is related to the volume electron concentration and is used as another indicator for the SEAL.