Spectroscopic ellipsometry studies of sol-gel-derived Cu-doped ZnO thin films

• Published in: Thin solid films Vol. 571; pp. 605 - 608
• Main Authors: Yang, Shenghong, Zhang, Yueli, Mo, Dang
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 28.11.2014; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Copper; Cross-disciplinary physics: materials science; rheology; Devices; Ellipsometry; Exact sciences and technology; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Liquid phase epitaxy; deposition from liquid phases (melts, solutions, and surface layers on liquids); Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Optical constants; Optical instruments, equipment and techniques; Optical properties; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Physics; Polarimeters and ellipsometers; Sol-gel method; Spectroscopic ellipsometry; Spectroscopy; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Thin film structure and morphology; Thin films; Wurtzite; X-ray diffraction; Zinc oxide; Zn1 − xCuxO films; Spectroscopic ellipsometry; Zn1−xCuxO films; Sol-gel method; Optical constants; Integrated optics; Photonic band gap; Refractive index; Doping; O films; XRD; Preferred orientation; Thin films; Cu; Zn; Optical properties; Wurtzite structure; Ultraviolet visible spectrum; Sol-gel process
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2014.02.097

Undoped and Cu-doped ZnO (Zn1−xCuxO: x=0.00, 0.03, 0.06, 0.10) films were prepared on Si(100) substrates by the sol-gel method, and the effects of Cu content on the structural, and optical properties of these films were investigated by X-ray diffraction (XRD) and UV–visible spectroscopic ellipsometry (SE). XRD patterns revealed that all the films were monophasic and had wurtzite structure with (002) preferential orientation along c-axis, indicating there were not any secondary phases. The measured UV–visible SE spectra were analyzed with an appropriate procedure to accurately determine the thickness and the optical constants. We found that the refractive index and the extinction coefficient increase with Cu content increasing. The optical band gap (Eg) has been calculated by classical Tauc formula, and the Eg values decrease as Cu content increasing. The variation in Eg with different Cu content revealed that the Eg value was affected by doping Cu. These mean that we can control the optical properties of the ZnO films by varying Cu content, which might be important in view of designing integrated optic devices. •Undoped and Cu-doped ZnO thin films were prepared by the sol-gel method.•The structural and optical properties of Cu-doped ZnO films were investigated.•Band gap Eg decreases as Cu content increasing.•The optical constants (n and k) increase with Cu content increasing.