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HL: Fachverband Halbleiterphysik

HL 21: Poster IB (Oxide semiconductors; II-VI and group IV semiconductors; Nanotubes and Buckyballs)

HL 21.12: Poster

Montag, 16. März 2015, 15:00–20:00, Poster B

Electrical conductivity and photoconductivity of single-crystalline In₂O₃ thin films — •Julius Rombach and Oliver Bierwagen — Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany

Although the gas sensing effect of conductometric metal oxide gas sensors is known to be surface-related, contributions from the bulk and the substrate interface are unclear. Due to the presence of a surface electron accumulation layer (SEAL), electrical conductivity of In₂O₃ thin films usually consists of contributions from the bulk material, the SEAL and the substrate interface. This study aims to disentangle these sources of conductivity using MBE grown single-crystalline In₂O₃ films. By thickness variation and Mg-doping with a subsequent annealing step in Oxygen, the bulk and interface contribution to the overall conductivity was altered. The SEAL contribution was influenced by oxygen plasma treatment of the surface, which removes the SEAL, and by UV illumination during conductivity measurements. In₂O₃ shows photoconductivity in the UV range with photon energies below the fundamental absorption edge, which is believed to be a photoreduction of oxygen adatoms on the In₂O₃ surface. Hence the contribution of the SEAL to overall conductivity can be increased by UV illumination. This can help to get a better understanding of the sensing mechanism of In₂O₃-based gas sensors and to achieve higher sensitivities by specifically influencing the particular contributions to electrical conductivity.