Growth of high quality ZnO thin films with a homonucleation on sapphire

Abstract

Growth and structural properties of ZnO films on ( 10 − 10 ) m -plane sapphire substrates by plasma-assisted molecular beam epitaxy Evolution of the electrical and structural properties during the growth of Al doped ZnO films by remote plasmaenhanced metalorganic chemical vapor deposition ZnO thin films were epitaxially grown on c-plane sapphire substrates by plasma-assisted molecular beam epitaxy. A low temperature homonucleation ZnO layer was found crucial at the interfacial region to absorb the defects formed by the lattice mismatch between the sapphire and ZnO, resulting in a smooth surface that enables smooth 2D epitaxial growth. High quality ZnO films were achieved after careful optimization of critical growth conditions: the sequence of Zn and O source shutters, growth temperature for both the ZnO nucleation and growth layer, and Zn/O ratio. Oxygen plasma pretreatment was not applied prior to the growth, thus shortening the growth time and reducing oxidation of the metallic sources. Resultant epitaxial ZnO films on sapphire demonstrated a root-mean-square surface roughness of 0.373 nm for 1 lm  1 lm atomic force microscope images with clear hexagonal structure and terrace steps. The x-ray diffraction full width at half maximum (FWHM) for x and x-2h ZnO (0002) triple-crystal rocking curves were measured to be 13 and 26 arc/s, respectively. This FWHM value is lower than any reported to date in the literature, with x and x-2h values indicating excellent coherence of the epitaxial layer along the interface and the growth direction, accordingly. These x-ray diffraction and surface roughness values are lower than those obtained using common nucleation layers such as MgO, indicating that growth with ZnO nucleation layers on sapphire may lead to higher quality electrical and optical devices.

Microstructural and optical properties of high-quality ZnO epitaxially grown on a LiGaO2 substrate

“…2,3 These unique properties make ZnO a potential material for applications in electronics, optoelectronics, acoustics, and sensing. [1][2][3] Various growth techniques have been used to fabricate ZnO thin lms, such as molecular beam epitaxy (MBE), 4,5 metal-organic chemical vapor deposition (MOCVD), 6,7 chemical vapor deposition (CVD), 8,9 pulsed laser deposition (PLD), 10,11 atomic layer deposition (ALD), 12,13 sputtering, 14,15 and sol-gel. 16 Among them, CVD gains particularly concerns because it is a simple and economic technique that has been widely used in the semiconductor industry to produce thin lms.…”

“…The crystal quality of asgrown ZnO thin lms is superior to previously reported ZnO lms grown on (001) LiGaO 2 substrate [25][26][27] and comparable to that of ZnO thin lms grown by MBE, MOCVD, PLD and ALD. [4][5][6][7][10][11][12][13] The underlying growth mechanism towards the high-quality ZnO lms is also discussed in detail.…”

Decolorization of Azo Dyes by Chemically and Biosynthesized ZnO Nanoparticles

“…These nanoparticles have different physical and chemical properties in accordance with the source of their synthesis. Recently, these ZnO NPs have gained much acclamation for dye degradation procedures 9,10,11 .…”

Decolorization of Azodyes by Chemically and Biosynthesized ZnO Nanoparticles

“…These nanoparticles have different physical and chemical properties in accordance with the source of their synthesis. Recently, these ZnO NPs have gained much acclamation for dye degradation procedures 9,10,11 . Biological synthesis of NPs using bacteria has been of special interest as it involves easy handling procedures, eco-friendly disposal methods and very easy for downstream processing.…”