Metallic clusters in nonstoichiometric gallium oxide films

Oxygen deficient gallium oxide films have been grown by pulsed-laser deposition. Depending on the growth conditions (oxygen pressure and laser power density), amorphous and insulating or partially crystalline and conducting gallium oxide films can be obtained. For very large oxygen deficiencies (Ga2O2.3), the oxide is not stable, and a phase separation leads to metallic Ga nanoparticles embedded in a stoichiometric Ga2O3 matrix. The resistivity measurements evidence the melting and freezing of Ga metallic nanoparticles in addition to their superconducting transition at low temperature. Due to small size both transitions are shifted as compared to the bulk properties. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3531536]