Browsing by Author "Cheng, Tsung-Chieh"

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Effect of annealing temperature for Si0.8Ge0.2 epitaxial thin films
(2008-03-15)
Chang, Yuan-Ming
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Dai, Ching-Liang
;
Cheng, Tsung-Chieh
;
Hsu, Che-Wei
;
機械工程學系
This study investigates the effect of annealing temperature on the Si0.8Ge0.2 epitaxial layers. The Si0.8Ge0.2 epitaxial layers were deposited by using ultrahigh vacuum chemical vapor deposition (UHVCVD) with different annealing temperatures ((400-1000 degrees C). Various measurement technologies, including high-resolution X-ray diffraction ((HRXRD), atomic force microscopy ((AFM) and interfacial adhesion tester, were used to characterize the materials properties of the SiGe epilayers. The experimental results showed that the SiGe epilayers gradually reduced lattice-mismatch to the underlying substrate as annealing temperature increased (from 400 to 800 degrees C), which resulted from a high temperature enhancing interdiffusion between the epilayers and the underlying substrate. In addition, the average grain size of the SiGe films increased from 53.3 to 58 nm with increasing annealing temperature. The surface roughness in thin film annealed at 800 degrees C was 0.46 nm. Moreover, the interfacial adhesion strength increased from 476 +/- 9 to 578 +/- 12 kg/cm(2) with increasing the annealing temperature. (c) 2007 Elsevier B.V. All rights reserved.
Effects of oxygen addition on physical properties of ZnO thin film grown by radio frequency reactive magnetron sputtering
(2011-02-03)
Hsu, Che-Wei
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Cheng, Tsung-Chieh
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Yang, Chun-Hui
;
Shen, Yi-Ling
;
Wu, Jong-Shinn
We deposited a ZnO thin film on a microslide glass substrate at room temperature by employing the RF reactive magnetron sputtering process. Our results revealed that deposition rate decreases by increasing O(2)/(Ar + O(2)) ratio that was caused by two mechanisms. The first mechanism was the reduction of plasma density and, thus, argon ion density; caused by the addition of highly electronegative oxygen. While the second mechanism was target poisoning caused by the oxidation of the target. Additionally, at the O(2)/(Ar + O(2)) ratio of similar to 0.3 and the help of XPS analysis the optimum stoichiometry of ZnO thin film (the highest binding energy and content fraction of O(1) peak (O-Zn bond)) and the best polycrystallinity (the lowest FWHM with largest grain size) was found. (C) 2010 Elsevier B.V. All rights reserved.
Investigation of Characteristics of Multi-Function ZnO Thin Film Deposited With Various Argon and Oxygen Ratios
(2009)
Hsu, Che-Wei
;
Cheng, Tsung-Chieh
;
Yang, Chun-Hui
;
Shen, Yi-Ling
;
Wu, Jong-Shin
The ZnO thin film was deposited on a glass substrate at RT by the RF reactive magnetron sputtering method. Structural, chemical, optical, and hydrophilic/hydrophobic properties are measured by using a surface profilometer, an x-ray diffractometry (XRD), an x-ray photoelectron spectroscopy (XPS), a UV-VIS spectrophotometer, and a contact angle system, respectively. Results show that the deposition rate decreases with increasing O(2)/(Ar+O(2)) ratio. In additiion, the best stoichiometric and quality of ZnO thin film was observed at 0.30 Of O(2)/(Ar+O(2)) ratio, which shows the smallest FWHM and the strongest O-Zn strength. Regardless Of O(2)/(Ar+O(2)) ratio effect or thickness effect, high transmittance (> 86%) in the visible region is observed, while the UV-shielding characteristics depend upon both the magnitude of film thickness. The film thickness plays a more prominent role in controlling optical properties, especially in the UV-shielding characteristics, than the O(2)/(Ar+O(2)) ratio. However, the hydrophobic characteristics can be obtained when the glass coating with ZnO thin films. In general, with properly coated ZnO thin film, we can obtain a glass substrate which is highly transparent in the visible region, has good UV-shielding characteristics, and possesses highly hydrophobic characteristics (self-clean capability), which is highly suitable for applications in the glass industries.
Nanocone SiGe antireflective thin films fabricated by ultrahigh-vacuum chemical vapor deposition with in situ annealing
(2010-05-03)
Chang, Yuan-Ming
;
Dai, Ching-Liang
;
Cheng, Tsung-Chieh
;
Hsu, Che-Wei
;
機械工程學系
In this study, we fabricated nanocone-presenting SiGe antireflection layers using only ultrahigh-vacuum chemical vapor deposition. In situ thermal annealing was adopted to cause SiGe clustering, yielding a characteristic nanocone array on the SiGe surface. Atomic force microscopy indicated that the SiGe nanocones had uniform height and distribution. Spectrophotometric measurements revealed that annealing at 900 degrees C yielded SiGe thin films possessing superior antireflective properties relative to those of the as-grown SiGe sample. We attribute this decrease in reflectance to the presence of the nanostructured cones. Prior to heat treatment, the mean reflectance of ultraviolet rays (wavelength <400 nm) of the SiGe thin film was ca. 61.7%; it reduced significantly to less than 28.5% when the SiGe thin film was annealed at 900 degrees C. Thus, the drop in reflectance of the SiGe thin film after thermal treatment exceeded 33%. (C) 2010 Elsevier B.V. All rights reserved.
Relation between the plasma characteristics and physical properties of functional zinc oxide thin film prepared by radio frequency magnetron sputtering process
(2010-02-01)
Hsu, Che-Wei
;
Cheng, Tsung-Chieh
;
Huang, Wen-Hsien
;
Wu, Jong-Shinn
;
Cheng, Cheng-Chih
The ZnO thin film was deposited on a glass substrate by a RF reactive magnetron sputtering method. Results showed that plasma density, electron temperature, deposition rate and estimated ion bombardment energy increase with increasing applied RF power. Three distinct power regimes were observed, which are strongly cot-related with plasma properties. In the low-power regime, the largest grain size was observed due to slow deposition rate. In the medium-power regime, the smallest grain size was found, which is attributed to insufficient time for the adatoms to migrate on substrate surface. In the high-power regime, relatively larger grain size was found due to very large ion bombardment energy which enhances the thermal migration of adatoms. Regardless of pure ZnO thin film or ZnO on glass, high transmittance (>80%) in the visible region can be generally observed. However, the film thickness plays a more important role for controlling optical properties, especially in the UV region, than the applied RF power. In general, with properly coated ZnO thin film, we can obtain a glass substrate which is highly transparent in the visible region, is of good anti-UV characteristics, and is highly hydrophobic, which is highly suitable for applications in the glass industry. (C) 2009 Elsevier B.V. All rights reserved.