ZnO- and TiO2-Based Semiconductor Films Prepared by Plasma Enhanced CVD Without any Carrier Gas

Plasma enhanced chemical vapor deposition (PECVD), one of the most widely used techniques in modern microelectronics, is firstly employed to prepare ferromagnetic ZnO-based and TiO₂-based magnetic semiconductors at low deposition temperature without any carrier gas. ZnO-based films show excellent photoluminescence at room temperature. All doped oxide films show room-temperature ferromagnetic behaviors by using superconducting quantum interference device measurements. Magnetic ions incorporating into host lattice and the exclusion of secondary phase in films are confirmed by microstructure analysis and magnetic results, such as XRD, XPS, PL and FC/ZFC. In order to gain insights into the effect of oxygen vacancies or nitrogen implantation on ferromagnetism of oxide-based semiconductors, all films were annealed in N₂ ambience at 900degC or treated in NH₃ or O₂ plasma at 350degC. The results indicated the crucial role of hole-carriers or oxygen- vacancies playing in the ferromagnetic coupling between magnetic ions in oxide-based semiconductors.