Multi-roles of Cu ions in the ferromagnetic properties of (Cu, Al)-codoped ZnO thin films

• Published in: Journal of crystal growth Vol. 332; no. 1; pp. 39 - 42
• Main Authors: Zhuo, Shi-Yi, Liu, Xue-Chao, Xiong, Ze, Yang, Jian-Hua, Shi, Er-Wei
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.2011; Elsevier
• Subjects: A1. Defects; A1. Doping; A3. Physical vapor deposition processes; B1. Oxides; B2. Magnetic materials; B2. Semiconducting II–VI materials; Condensed matter: structure, mechanical and thermal properties; Copper; Cross-disciplinary physics: materials science; rheology; Crystal defects; Defects and impurities: doping, implantation, distribution, concentration, etc; Deposition by sputtering; Discharges for spectral sources (including inductively coupled plasmas); Electric discharges; Exact sciences and technology; Ferromagnetic materials; Ferromagnetism; Inductively coupled plasma; Ion and electron beam-assisted deposition; ion plating; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Physics of gases, plasmas and electric discharges; Physics of plasmas and electric discharges; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Thin films; Zinc oxide; A1. Doping; A3. Physical vapor deposition processes; B1. Oxides; B2. Semiconducting II–VI materials; B2. Magnetic materials; A1. Defects; Temperature dependence; Electrical properties; Doping; Hall effect; Thin films; Inductively coupled plasma; Valence; II-VI semiconductors; Temperature effects; Physical vapor deposition; Zinc oxide; B2. Semiconducting II-VI materials; Magnetic materials; Copper; Plasma deposition; Magnetic properties
• ISSN: 0022-0248; 1873-5002
• DOI: 10.1016/j.jcrysgro.2011.07.028

(Cu, Al)-codoped ZnO films have been prepared by inductively coupled plasma enhanced physical vapor deposition (ICP-PVD) system at different substrate temperatures ranging from room temperature to 527 °C. The electrical and magnetic properties, defect and chemical valence state were studied. Room-temperature ferromagnetism was observed in all of the (Cu, Al)-codoped ZnO films. It was found that Cu ions played an important role in the ferromagnetism origin and showed multiple roles in the semi-insulating and conductive regimes according to the Hall effect measurements. For the semi-insulating regime, Cu ions showed mixed valence states of +1/+2 and acted as local charge reservoirs. For the conductive regime, Cu ions showed dominant valence states of +2 and acted as magnetic ions. ► (Cu, Al)-codoped ZnO thin films have been prepared by ICP-PVD method. ► Room-temperature ferromagnetism was observed in all the as-grown samples. ► The effect of Cu-doping in inducing ferromagnetism of (Cu, Al)-codoped ZnO thin films was studied. ► Cu ions played multiple roles in the semi-insulating and conductive (Cu, Al)-codoped ZnO thin films.