Growth and electronic properties of ZnO epilayers by plasma-assisted molecular beam epitaxy

• Published in: Journal of electronic materials Vol. 34; no. 6; pp. 699 - 703
• Main Authors: MURPHY, T. E, CHEN, D. Y, PHILLIPS, J. D
• Format: Conference Proceeding Journal Article
• Language: English
• Published: New York, NY Institute of Electrical and Electronics Engineers 01-06-2005; Springer Nature B.V
• Subjects: Applied sciences; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Diffraction; Electronics; Exact sciences and technology; High temperature; Materials; Molecular beam epitaxy; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Physics; Substrates; Thin films; X-rays; Zinc oxides; molecular beam epitaxy (MBE); Plasma; Electronic properties; Temperature; electrical properties; Charge carrier density; Transition element compounds; X ray; Epitaxial film; X ray diffraction; Inorganic compound; Thin film; Substrate; Electronic structure; Sapphire; Rocking curve; Growth mechanism; Molecular beam epitaxy; Zinc oxide; ZnO
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-005-0006-8

ZnO thin films were grown on c-plane sapphire substrates by plasma-assisted molecular beam epitaxy (MBE). The crystalline properties of the layers as measured by x-ray diffraction were found to improve with lower growth temperatures, where the full-width at half-maximum (FWHM) of the x-ray rocking curves was shown to be in the range of 100 to 1,100 arcsec. The electronic properties were found to improve for higher growth temperatures, with n-type carrier concentration and electron mobility in the range of 1 × 10^sup 17^-5 × 10^sup 18^ cm^sup -3^ and 80-36 cm^sup 2^/Vs, respectively. Photoluminescence (PL) measurements indicated that growth at higher temperatures provided superior band edge radiative emission, while growth at lower temperatures resulted in significant deep level radiative emission centered at 2.35 eV. Photoconductive decay measurements exhibit a slow decay indicating the presence of hole traps, where Zn vacancies are believed to be the source of both the slow decay and the deep level emission observed in PL spectra. [PUBLICATION ABSTRACT]