Epitaxial growth of Sc-doped ZnO films on Si by sol–gel route

• Published in: Applied surface science Vol. 255; no. 11; pp. 5781 - 5788
• Main Authors: Sharma, Ruchika, Sehrawat, Kiran, Wakahara, Akihiro, Mehra, R.M.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15-03-2009; Elsevier
• Subjects: Annealing; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Ii-vi semiconductors; Materials science; Materials synthesis; materials processing; Methods of deposition of films and coatings; film growth and epitaxy; Morphology; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Photoluminescence; Physics; Scandium; Sol-gel processing, precipitation; Sol–gel; Structure and morphology; thickness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Theory and models of film growth; Thin film structure and morphology; Zinc oxide; 68.37.Hk; 68.37.Ps; Annealing; 81.20.Fw; Morphology; Scandium; Photoluminescence; 61.05.jh; Zinc oxide; Sol–gel; 68.55.A; 61.05.cp; Atomic force microscopy; Inorganic compounds; Epitaxy; Roughness; XRD; RHEED; Surface structure; Ostwald ripening; p type semiconductor; Sol-gel process; Temperature dependence; Scanning electron microscopy; Phase transformations; Sol-gel; Transition element compounds; Doped materials; Surface diffusion; Scandium additions; Coalescence
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2009.01.004

The epitaxial growth of doped ZnO films is of great technological importance. Present paper reports a detailed investigation of Sc-doped ZnO films grown on (1
0
0) silicon p-type substrates. The films were deposited by sol–gel technique using zinc acetate dihydrate as precursor, 2-methoxyethanol as solvent and monoethanolamine (MEA) as a stabilizer. Scandium was introduced as dopant in the solution by taking 0.5
wt%
1
1
Ruchika Sharma, P. K. Shishodia, A. Wakahara and R. M. Mehra, Materials Science-Poland 27 (2009) Ist issue.
of scandium nitrate hexahydrate. The effect of annealing on structural and photoluminescence properties of nano-textured Sc-doped films was investigated in the temperature range of 300–550
°C. Structural investigations were carried out using X-ray diffraction, scanning electron microscopy and atomic force microscopy. X-ray diffraction study revealed that highly
c-axis oriented films with full-width half maximum of 0.21° are obtained at an annealing temperature of 400
°C. The SEM images of ZnO:Sc films have revealed that coalescence of ZnO grains occurs due to annealing. Ostwald ripening was found to be the dominant mass transport mechanism in the coalescence process. A surface roughness of 4.7
nm and packing density of 0.93 were observed for the films annealed at 400
°C. Room temperature photoluminescence (PL) measurements of ZnO:Sc films annealed at 400
°C showed ultraviolet peak at about (382
nm) with FWHM of 141
meV, which are comparable to those found in high-quality ZnO films. The films annealed below or above 400
°C exhibited green emission as well. The presence of green emission has been correlated with the structural changes due to annealing. Reflection high energy electron diffraction pattern confirmed the nearly epitaxial growth of the films.