Browsing by Author "Tseng, C. H."

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Effects of sputtering pressure and Al buffer layer thickness on properties of AZO films grown by rf magnetron sputtering
(2010-08-20)
Tseng, C. H.
;
Wang, W. H.
;
Chang, H. C.
;
Chou, C. P.
;
Hsu, C. Y.
Transparent and conductive Al-doped (2 wt.%) zinc oxide (AZO) films were deposited on inexpensive soda-lime glass substrates by using rf magnetron sputtering at room temperature. This study analyzed the effects of argon sputtering pressure, which varied in the range from 0.46 to 2.0 Pa, on the morphological, electrical and optical properties of AZO films. The only (0 0 2) diffraction peak of the film were observed at 20 similar to 34.45 degrees, exhibiting that the AZO films had hexagonal ZnO wurtzite structure, and a preferred orientation with the c-axis perpendicular to the substrate. By applying a very thin aluminum buffer layer with the thickness of 2 nm, findings show that the electrical resistivity was 9.46 x 10(-4) Omega-cm, and the average optical transmittance in the visible part of the spectra was approximately 81%. Furthermore, as for 10 nm thick buffer layer, the electrical resistivity was lower, but the transmittance was decreased. (C) 2010 Elsevier Ltd. All rights reserved.
GROWTH OF AZO FILMS ON BUFFER LAYERS BY RF MAGNETRON SPUTTERING
(2010-12-20)
Chen, C. W.
;
Tseng, C. H.
;
Hsu, C. Y.
;
Chou, C. P.
;
Hou, K. H.
Al(2)O(3)-doped zinc oxide (in AZO, the Al(2)O(3) contents are approximately 2 wt.%) films have been grown by radio frequency (RF) magnetron sputtering at room temperature under varied sputtering pressures ranging from 3.5-15 mTorr. The electrical resistivity of AZO films is about 2.22 x 10(-3) Omega cm (sheet resistance similar to 89 Omega/square for a thickness similar to 250 nm), and the visible range transmittance is a bout 80% at the argon sputtering pressure of 15 mTorr and a RF power of 100 W. This study analyzes the structural, morphological, electrical and optical properties of AZO thin films grown on soda-lime glass substrate with 2, 5, and 10 nm thick Al buffer layers (and SiO(2) buffer). For the films deposited on the 2 nm thick Al buffer layer, we obtained ac-axis-oriented AZO/Al thin film on glass with the XRD full-width at half maximum (FWHM) of 0.31 and root mean square (RMS) surface roughness of about 3.22 nm. The lowest resistivity of 9.46 x 10(-4) Omega cm (sheet resistance similar to 37.87 Omega/square for a thickness similar to 250 nm) and a high transmittance (80%) were obtained by applying a 2 nm thick Al buffer layer. In contrast, the resistivity was slightly increased by applying the SiO(2) buffer layer.
Structural and optoelectronic properties of Al-doped zinc oxide films deposited on flexible substrates by radio frequency magnetron sputtering
(2011-09-01)
Tseng, C. H.
;
Huang, C. H.
;
Chang, H. C.
;
Chen, D. Y.
;
Chou, C. P.
Al-doped zinc oxide (AZO) thin films were deposited onto flexible polyethylene terephthalate substrates, using the radio frequency (RF) magnetron sputtering process, with an AZO ceramic target (The Al(2)O(3) content was about 2 wt.%). The effects of the argon sputtering pressure (in the range from 0.66 to 2.0 Pa), thickness of the Al buffer layer (thickness of 2, 5, and 10 nm) and annealing in a vacuum (6.6 x 10(-4) Pa), for 30 min at 120 degrees C, on the morphology and optoelectronic performances of AZO films were investigated. The resistivity was 9.22 x 10(-3) Omega cm, carrier concentration was 4.64 x 10(21) cm(-3), Hall mobility was 2.68 cm(2)/V s and visible range transmittance was about 80%, at an argon sputtering pressure of 2.0 Pa and an RF power of 100 W. Using an Al buffer decreases the resistivity and optical transmittance of the AZO films. The crystalline and microstructure characteristics of the AZO films are improved by annealing. (C) 2011 Elsevier BM. All rights reserved.