Thickness dependence of microstructural evolution of ZnO films deposited by rf magnetron sputtering

The microstructural evolution, including preferred orientation and surface morphology, of ZnO films deposited by rf magnetron sputtering was investigated with increasing film thickness. Preferred orientation of the ZnO films changed from (0002) → (1011) → (1120) and fine and dense columnar grains also changed to large elongated grains with increasing thickness. Such selective texture growth was explained with an effect of highly energetic species bombardment on the growing film surface. The relationship between preferred orientation change and microstructural evolution was also discussed.

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Self-Texture Control of ZnO Films Prepared by Reactive RF Magnetron Sputtering

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.605.219 ◽

2014 ◽

Vol 605 ◽

pp. 219-222

Author(s):

Petr Novák ◽

Pavol Šutta ◽

M. Netrvalová ◽

Jan Říha ◽

Rostislav Medlín

Keyword(s):

Magnetron Sputtering ◽

Crystal Surface ◽

Rf Magnetron Sputtering ◽

Film Structure ◽

Acoustic Resonator ◽

Preferred Orientation ◽

Zno Films ◽

Potential Applications ◽

Horizontal Wave ◽

Shear Horizontal

Zinc Oxide (ZnO) is a wide bandgap semiconductor material which can be successfully used for wide variety of potential applications such as biosensors or acoustic resonator devices. ZnO normally crystallizes in the wurtzitestructure with c-axis (001) preferred orientation. However, for bio-sensing in liquids, it is necessary to generate a shear horizontal mode wave, where the wave displacement is within the plane of the crystal surface. For generation of such a shear horizontal wave, a-axis film textures such as the (110) or (100) is necessary. This work is focused on the preferred orientation control of ZnO film prepared by RF magnetron sputtering. It is found that preferred orientation can be controlled by substrate bias and substrate temperature during deposition without the use of expensive crystalline substrates. There are three areas of operating parameters when the structure of the ZnO films is dominated by different preferred orientation. Moreover, the film annealing was performed to enhance the film structure.

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Al-Doping Effect on the Surface Morphology of ZnO Films Grown by Reactive RF Magnetron Sputtering

Materials Sciences and Applications ◽

10.4236/msa.2013.412096 ◽

2013 ◽

Vol 04 (12) ◽

pp. 761-767 ◽

Cited By ~ 5

Author(s):

Erica Pereira da Silva ◽

Michel Chaves ◽

Gilvan Junior da Silva ◽

Larissa Baldo de Arruda ◽

Paulo Noronha Lisboa-Filho ◽

...

Keyword(s):

Surface Morphology ◽

Magnetron Sputtering ◽

Rf Magnetron Sputtering ◽

Doping Effect ◽

Zno Films ◽

Al Doping ◽

Reactive Rf Magnetron Sputtering

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Effects of substrates roughness on c-axis preferred orientation of ZnO films deposited by rf magnetron sputtering

MRS Proceedings ◽

10.1557/proc-672-o8.20 ◽

2001 ◽

Vol 672 ◽

Author(s):

Jae Bin Lee ◽

Sanghyon Kwack ◽

Hyeong Joon Kim

Keyword(s):

Surface Roughness ◽

Magnetron Sputtering ◽

Radio Frequency ◽

Atomic Force Microscope ◽

Substrate Surface ◽

Rf Magnetron Sputtering ◽

Preferred Orientation ◽

Zno Films ◽

Atomic Force ◽

Substrate Surface Roughness

ABSTRACTWe investigated the effect of substrate surface roughness on c-axis preferred orientation of ZnO films deposited by radio frequency (rf) magnetron sputtering. We used as substrates a bare Si(100), evaporated Au/Si(100), evaporated Al/Si(100), and sputtered Al/Si(100), of which rms roughness by atomic force microscope (AFM) were 0.127, 1.71, 2.11, and 6.5∼11.8 nm, respectively. The crystallinity and the c-axis preferred orientation of ZnO films strongly depended on the surface roughness of the used substrates.

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Preferred orientation and microstructure of Ni-Zn-Cu ferrite thin films deposited by rf magnetron sputtering

Journal of Materials Research ◽

10.1557/jmr.1994.2425 ◽

1994 ◽

Vol 9 (9) ◽

pp. 2425-2433 ◽

Cited By ~ 10

Author(s):

Hae Seok Cho ◽

Min Hong Kim ◽

Hyeong Joon Kim

Keyword(s):

Thin Films ◽

Magnetron Sputtering ◽

Process Parameters ◽

Rf Magnetron Sputtering ◽

Preferred Orientation ◽

Ferrite Film ◽

Rf Power ◽

Columnar Grains ◽

Ferrite Thin Films ◽

Ferrite Films

We have investigated the effects of process parameters such as rf power, substrate, and gas pressure PAr on preferred orientation, microstructure, and magnetic properties of Ni-Zn-Cu ferrite thin films deposited by conventional rf magnetron sputtering. The texture structure was developed in the ferrite films deposited on the SiO2/Si(100) substrate at low rf power conditions. The ferrite film on the Si(111) substrate always had (111) texture irrespective of process parameters due to lattice matching, but the texture of the ferrite film on SiO2/Si(100) changed from (111) to (100) and finally returned to (111) orientation again with decreasing PAr. Such behavior would occur presumably due to the characteristic atomic stacking sequence corresponding to a given condition of the ion bombardment. The ferrite films deposited at low PAr had a denser microstructure consisting of tightly packed columnar grains with a smoother surface, better adhesion to the substrate, and better crystallinity than those at high PAr. Hc‖ of ferrite film deposited at low PAr was larger than that at high PAr and also larger than Hc⊥ of that deposited at the same PAr because larger compressive stress was induced at low PAr than at high PAr.

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The Preparation of the Highly Preferred Orientation of Wurtzite Structure Zinc Oxide Films

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.936.287 ◽

2014 ◽

Vol 936 ◽

pp. 287-292

Author(s):

Lei Lei Lan ◽

Dan Zhou ◽

Guang Rui Gu ◽

Bao Jia Wu ◽

Lian Hua Tian

Keyword(s):

Zinc Oxide ◽

Substrate Temperature ◽

Crystalline Structure ◽

Film Surface ◽

Rf Magnetron Sputtering ◽

Preferred Orientation ◽

Wurtzite Structure ◽

Zno Films ◽

Zno Film ◽

Si Substrates

Zinc oxide (ZnO) films are prepared on n-Si substrates by means of radio frequency (RF) magnetron sputtering method. The influences of substrate temperature on the crystal orientation and crystalline structure of ZnO films are investigated by X-ray diffraction (XRD) and Raman spectroscopy. The surface morphologies are studied by scanning electron microscope (SEM). It is indicated that ZnO films with wurtzite structure were successfully prepared. When the substrate temperature reduced to 100°C, the wurtzite structure with highly preferred orientation along the (002) plane of the ZnO film is prepared and the elliptical shape particles distributed uniformly on the ZnO film surface. The higher substrate temperature can offer more kinetic energy for mobility of particle on the surface to achieve other crystalline growth, resulting in the highly c-axis-oriented crystalline structure is destroyed.

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Effect of Graded Bias on Microstructure and Hardness of CrNX Films

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.154-155.1476 ◽

2010 ◽

Vol 154-155 ◽

pp. 1476-1480

Author(s):

Shu Yong Tan ◽

Xu Hai Zhang ◽

Xiang Jun Wu ◽

Feng Fang

Keyword(s):

Surface Morphology ◽

Magnetron Sputtering ◽

Preferred Orientation ◽

Dc Magnetron Sputtering ◽

Dense Structure ◽

Constant Bias ◽

High Bias ◽

Relationship Of ◽

The Relationship

CrNx films were synthesized under graded/constant bias by DC magnetron sputtering. In the present work, the graded bias deposited CrNx films have both (111) and (200) orientations while only (111) orientation in low bias (-20 V) and (200) orientation in high bias (-200 V). Both the magnitude of bias and preferred orientation result in the variation in their surface morphology from pyramidal (loosen) to cellular (dense) structure. The hardness of the graded films is between the low and high constant bias ones. The relationship between the hardness and bias gradient is similar with the relationship of hardness and the content of (200) preferred crystallites, which implies the fine (200) preferred crystallites is an important factor for hardness of graded bias films.

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Deposition of Piezoelectric ZnO Films by RF Magnetron Sputtering and its Application to SAW Devices

MRS Proceedings ◽

10.1557/proc-1035-l05-16 ◽

2007 ◽

Vol 1035 ◽

Cited By ~ 1

Author(s):

Seol Hee Choi ◽

Chan Hyoung Kang

Keyword(s):

Magnetron Sputtering ◽

Rf Magnetron Sputtering ◽

Silicon Wafers ◽

Center Frequency ◽

High Resistivity ◽

Chemical Vapor Deposition Method ◽

Zno Films ◽

Optimum Process ◽

Optimum Conditions ◽

Saw Devices

AbstractHighly c-axis oriented, dense, and fine-grained polycrystalline ZnO films with smooth surface and high resistivity were deposited on 4 inch silicon wafers by employing ZnO targets in a radio-frequency (RF) magnetron sputtering system. By changing applied RF power, substrate temperature and O2/Ar gas ratio, the optimum process parameters were found to be 150 W, 200 °C and 30/70, respectively. Applying the ZnO films deposited under these optimum conditions, surface acoustic wave (SAW) devices of ZnO/IDT/SiO2/Si structure were fabricated by conventional photolithography and etching processes. The interdigital transducers (IDT), made of the aluminum deposited by DC magnetron sputter, were patterned as 2.5/2.5 μm of finger width/spacing. Another type of SAW filter of IDT/ZnO/diamond/Si structure was fabricated. In this structure, high-quality nanocrystalline diamond (NCD) films were deposited on 4 inch silicon wafers by direct current (DC) plasma assisted chemical vapor deposition method using H2-CH4 mixture as precursor gas. On the top of the diamond films, ZnO films were deposited under the optimum conditions. The aluminum IDT pattern was fabricated on the ZnO/diamond layered films. The characteristics of the fabricated SAW devices were evaluated in terms of center frequency, insertion loss, and wave propagation velocity.

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