Photoinduced reversible conductivity and photoconductivity changes in transparent amorphous and micro-crystalline In2O3-x films

The dark conductivity σ of poorly conducting In2O3-x films can be enhanced by orders of magnitude by blue or UV light exposure at any temperature between 4.2K and 00 K. The resulting high σ state of amorphous films reverts back to its original low σ state upon heating to 400K in an inert gas and can be repeated many times. In crystalline films the high σ state is stable to higher temperatures where annealing leads to some outdiffusion of oxygen and hence to a conductivity increase which can only be reversed by external re-oxidation. The photoinduced increase in dark conductivity is accompanied by an increase in photoconductivity at hv = 0.6 or 2eV by a factor of 107 at 4.2K