Spectroscopic Understanding of Structural and Electrical Property Variations in Dopant-Free ZnO Films

Physical property variation in dopant-free ZnO films was investigated. Film annealing under various environments (O2, in-Air, N2 and vacuum) resulted in better crystallinity than in the as-grown film. In particular, the film annealed under the N2 environment showed better crystallinity and electrical properties than films annealed in other environments. Based on spectroscopic analysis, we found a correlation between physical (structural, electrical) and chemical properties: The crystallinity of ZnO films is closely related to ZnO bonding, whereas carrier concentration is associated with VO (oxygen vacancy).