Electrical and optical properties of In2O3 nanoparticles prepared by MOCVD

High sensitive ozone sensors working at room temperature were demonstrated based on In2O3 nanoparticles, which were deposited by metal organic chemical vapor deposition (MOCVD). The resistance of the In2O3 particle containing layer can be tuned over five orders of magnitude after ultraviolet light illumination and oxidation by ozone containing gases. To investigate the light induced effect on In2O3 layer, In2O3 nanoparticles were deposited at different substrate temperatures by MOCVD and the electrical and optical properties of the layers were analyzed. It was found that the layers deposited above 220°C showed a typical linear I-V behavior while the layers grown below 220°C revealed a classical Schottky behavior. Furthermore, the In2O3 layers deposited below the critical temperature demonstrated not only an increasing absorption at 3.7 eV, which is the optical band gap of In2O3 thin films, but also two additional absorption peaks located at about 4.3 and about 5.3 eV, respectively. These differences in structural, electrical and optical properties of In2O3 layers lead to different ozone sensing properties.