Browsing by Author "Yang, Ping-Feng"

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Characteristics of ZnO thin films prepared by radio frequency magnetron sputtering
(2008-03-01)
Yang, Ping-Feng
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Wen, Hua-Chiang
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Jian, Sheng-Rui
;
Lai, Yi-Shao
;
Wu, Sean
We investigated in this study structural and nanomechanical properties of zinc oxide (ZnO) thin films deposited onto Langasite substrates at 200 degrees C through radio frequency magnetron sputtering with an radio frequency power at 200 W in an O(2)/Ar gas mixture for different deposition time at 1, 2, and 3 h. Surface morphologies and crystalline structural characteristics were examined using X-ray diffraction, scanning electron microscopy, and atomic force microscopy. The deposited film featured a polycrystalline nature, with (100), (002), and (101) peaks of hexagonal zinc oxide at 31.75 degrees, 34.35 degrees, and 36.31 degrees. As the deposition time increased, the ZnO film became predominantly oriented along the c-axis (002) and the surface roughness decreased. Through Berkovich nanoindentation following a continuous stiffness measurement technique, the hardness and Young's modulus of ZnO thin films increased as the deposition time increased, with the best results being obtained for the deposition time of 3 h. In addition, surface acoustic wave properties of ZnO thin films were also presented. (C) 2007 Elsevier Ltd. All rights reserved.
Characterizations of ZnO thin films deposited onto langasite substrates by r.f. magnetron sputtering
(2007)
Yang, Ping-Feng
;
Wen, Hua-Chiang
;
Jian, Sheng-Rui
;
Lail, Yi-Shao
;
Wu, Sean
We investigated in this study structural and nanomechanical properties of zinc oxide (ZnO) thin films deposited onto langasite substrates at 200 degrees C through r.f. magnetron sputtering with an r.f. power at 200 W in an O2/Ar gas mixture for different deposition time at 1, 2, and 3 h. Surface morphologies and crystalline structural characteristics were examined using x-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The deposited film featured a polycrystalline nature, with (100), (002), and (101) peaks of hexagonal ZnO at 31.75 degrees, 34.35 degrees, and 36.31 degrees. As the deposition time increased, the ZnO film became predominantly oriented along the c-axis (002) and the surface roughness decreased. Through Berkovich nanoindentation following a continuous stiffness measurement (CSM) technique, the hardness and Young\'s modulus of the ZnO thin films increased as the deposition time increased, with the best results being obtained for the deposition time of 3 h.
Evaluating nanotribological behavior of annealing Si(0.8)Ge(0.2)/Si films
(2011-12-01)
Wu, Ming-Jhang
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Wen, Hua-Chiang
;
Wu, Shyh-Chi
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Yang, Ping-Feng
;
Lai, Yi-Shao
In this study, the SiGe epilayers were created on silicon substrate by using ultra-high vacuum chemical vapor deposition (UHV/CVD) and followed by annealing procedures. The frictional behaviors of SiGe epilayers were subjected to nanoscratch techniques under a ramping load. Damage caused by scratching was examined by atomic force microscopy (AFM); the results showed that the pile-up phenomena were significant on both sides of the scratch in the case of SiGe epilayers, suggesting that the dynamic deformation behavior was dominated by cracking as ploughing occurred during scratching. In addition, the SiGe epilayers films with different annealed conditions exhibited the decrease in coefficient of friction (COF), indicating the higher shear resistance exist in annealed SiGe epilayers, which probably affect the film uniformity and device yield under IC process integration. (C) 2011 Elsevier Ltd. All rights reserved.
Evaluating nanotribological behavior of annealing Si0.8Ge0.2/Si films
(2011-12-01)
Wu, Ming-Jhang
;
Wen, Hua-Chiang
;
Wu, Shyh-Chi
;
Yang, Ping-Feng
;
Lai, Yi-Shao
In this study, the SiGe epilayers were created on silicon substrate by using ultra-high vacuum chemical vapor deposition (UHV/CVD) and followed by annealing procedures. The frictional behaviors of SiGe epilayers were subjected to nanoscratch techniques under a ramping load. Damage caused by scratching was examined by atomic force microscopy (AFM); the results showed that the pile-up phenomena were significant on both sides of the scratch in the case of SiGe epilayers, suggesting that the dynamic deformation behavior was dominated by cracking as ploughing occurred during scratching. In addition, the SiGe epilayers films with different annealed conditions exhibited the decrease in coefficient of friction (COF), indicating the higher shear resistance exist in annealed SiGe epilayers, which probably affect the film uniformity and device yield under IC process integration. (C) 2011 Elsevier Ltd. All rights reserved.
Evaluation of the nanoindentation behaviors of SiGe epitaxial layer on Si substrate
(2010-01-01)
He, Bo-Ching
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Cheng, Chun-Hu
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Wen, Hua-Chiang
;
Lai, Yi-Shao
;
Yang, Ping-Feng
In this paper, ultra-high vacuum chemical vapor deposition (UHV/CVD) was employed to synthesize silicon-germanium (SiGe), and sequence to endure annealing treatment. Morphological characterization, roughness, and microstructural morphology were observed by means of scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The elements distribution, crystallographic, and nanomechanical behavior were carried out using energy-dispersive Xray spectroscopy (EDS) mapping technique, X-ray diffraction (XRD), and nanoindentation technique. The annealing treated SiGe leads to the 2D germanium segregation on the surface. The phenomenon is interpreted in terms of dislocation-induced structural changes in annealing treatment, Thus, the dislocation propagation in the microstructure was observed. Subsequently hardness and elastic modulus were increased because of a comparatively unstable microstructure after annealing treatment. (C) 2009 Elsevier Ltd. All rights reserved.
Mechanical properties of InGaN thin films deposited by metal-organic chemical vapor deposition
(2008-06-15)
Jian, Sheng-Rui
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Jang, Jason Shian-Ching
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Lai, Yi-Shao
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Yang, Ping-Feng
;
Yang, Chu-Shou
We report in this study characteristics of InGaN thin films developed by metal-organic chemical vapor deposition (MOCVD) at various growth temperatures. The effect of deposition temperatures on microstructures and mechanical properties are examined using X-ray diffraction (XRD), scanning probe microscopy (SPM), and nanoindentation techniques. The XRD analysis shows no evidence of phase separation for InGaN thin films. The SPM micrographs indicate that the films have relatively smooth surfaces. Hardness and Young's modulus of InGaN thin films vary according to the deposition temperature. As the deposition temperature increases from 730 to 790 degrees C, the grain size increases from 28 to 52 nm. Hardness for InGaN thin films dropped from 13.8 to 17.6 GPa in accordance with the increase of the grain size. By fitting experimental data with the Hall-Petch equation, a probable lattice friction stress of 3.48 GPa and Hall-Petch constant of 73.15 GPa nm(1/2) are obtained. (C) 2007 Elsevier B.V. All rights reserved.
Mechanical properties of the hexagonal HoMnO(3) thin films by nanoindentation
(2010-10-22)
Yen, Cheng-Yo
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Jian, Sheng-Rui
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Lai, Yi-Shao
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Yang, Ping-Feng
;
Liao, Ying-Yen
The structural and nanomechanical characteristics of the hexagonal HoMnO(3) (HMO) thin films are investigated by means of X-ray diffraction (XRD), atomic force microscopy (AFM) and nanoindentation techniques in this study. The HMO thin films were deposited on YSZ(1 1 1) substrates by pulsed laser deposition (PLD). The XRD results reveal only pure (0 0 0 1)-oriented hexagonal HMO reflections without any discernible traces of impurity or secondary phases. Nanoindentation results exhibit discontinuities in the load-displacement curve (so-called multiple "pop-ins" event) during loading, indicating possible involvement of dislocation activities. No discontinuities were observed on unloading segment of the load-displacement curve. Continuous stiffness measurements (CSM) technique was carried out in the nanoindentation tests to determine the hardness and Young's modulus of the hexagonal HMO thin films. The obtained hardness and Young's modulus of the hexagonal HMO thin films are 14.2 +/- 0.7 GPa and 219.2 +/- 10.6 GPa, respectively with the room-temperature fracture toughness being in the order of 0.4 +/- 0.2 MPa m(1/2). (c) 2010 Elsevier B.V. All rights reserved.
Mechanical properties of the hexagonal HoMnO3 thin films by nanoindentation
(2010-10-22)
Yen, Cheng-Yo
;
Jian, Sheng-Rui
;
Lai, Yi-Shao
;
Yang, Ping-Feng
;
Liao, Ying-Yen
The structural and nanomechanical characteristics of the hexagonal HoMnO3 (HMO) thin films are investigated by means of X-ray diffraction (XRD), atomic force microscopy (AFM) and nanoindentation techniques in this study. The HMO thin films were deposited on YSZ(1 1 1) substrates by pulsed laser deposition (PLD). The XRD results reveal only pure (0 0 0 1)-oriented hexagonal HMO reflections without any discernible traces of impurity or secondary phases. Nanoindentation results exhibit discontinuities in the load-displacement curve (so-called multiple "pop-ins" event) during loading, indicating possible involvement of dislocation activities. No discontinuities were observed on unloading segment of the load-displacement curve. Continuous stiffness measurements (CSM) technique was carried out in the nanoindentation tests to determine the hardness and Young's modulus of the hexagonal HMO thin films. The obtained hardness and Young's modulus of the hexagonal HMO thin films are 14.2 +/- 0.7 GPa and 219.2 +/- 10.6 GPa, respectively with the room-temperature fracture toughness being in the order of 0.4 +/- 0.2 MPa m(1/2). (c) 2010 Elsevier B.V. All rights reserved.
Morphological, structural, and mechanical characterizations of InGaN thin films deposited by MOCVD
(2008-09-08)
Yang, Ping-Feng
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Jian, Sheng-Rui
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Lai, Yi-Shao
;
Yang, Chu-Shou
;
Chen, Rong-Sheng
Presented in this study are surface roughness, crystalline structure, and nanomechanical properties of InGaN thin films deposited under various growth temperatures, obtained by means of X-ray diffraction (XRD), atomic force microscopy (AFM), and nanoindentation techniques. The InGaN thin films with different In contents were deposited on sapphire substrates through a metal-organic chemical-vapor deposition (MOCVD) system. Changes in mechanical properties for InGaN thin films are discussed in conjunction with deposition temperature, surface morphology and crystalline structure. The XRD measurements showed that there was no phase separation of In as the In composition went from 25 at.% to 34 at.%. Moreover, both XRD and AFM showed larger grain and surface roughness in In0.25Ga0.75N thin films. Nanoindentation results indicate that hardness and Young's modulus both decreased as the indentation depth increased. The contact stress-strain relationships were also analyzed. (C) 2007 Elsevier B.V. All fights reserved.
Nanoindentation-induced phase transformation of silicon
(2006)
Yang, Ping-Feng
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Jian, Sheng-Rui
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Lai, Yi-Shao
;
Chen, Tsan-Hsien
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Chen, Rong-Sheng
In this study, the deformation behavior of single-crystal Si (100) was examined using nanoindentation, followed by analysis using cross-sectional transmission electron microscopy (XTEM), scanning electron microscopy (SEM), and Raman microspectroscopy. XTEM samples were prepared by focused ion beam (FIB) milling to accurately position the cross-section through the indentations. The deformation via phase transformation was clearly observed with micro-Raman and XTEM, showing the presence of high-pressure crystalline phases Si-Ill and Si-XII following pressure release. The indentation fracture toughness of Si is also discussed.
Nanomechanical characteristics of annealed Si/SiGe superlattices
(2011-08-15)
Wu, Ming-Jhang
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Wen, Hua-Chiang
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Wu, Shyh-Chi
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Yang, Ping-Feng
;
Lai, Yi-Shao
In this study, the nanomechanical damage was investigated on the annealed Si/SiGe strained-layer superlattices (SLSs) deposited using an ultrahigh-vacuum chemical vapor deposition (UHVCVD). Nanoscratch, nanoindenter, atomic force microscopy (AFM), and transmission electron microscopy (TEM) techniques were used to determine the nanomechanical behavior of the SiGe films. With a constant force applied, greater hardness number and larger coefficients of friction (mu) were observed on the samples that had been annealed at 600 degrees C, suggesting that annealing of the Si/SiGe SLSs can induce greater shear resistance. AFM morphological studies of the Si/SiGe SLSs revealed that pile-up phenomena occurred on both sides of each scratch, with the formation of some pellets and microparticles. The Si/SiGe SLSs that had been subjected to annealing under various conditions exhibited significantly different features in their indentation results. Indeed, the TEM images reveal slight dislocation propagation in the microstructures. Thus, the hardness and elastic modulus can be increased slightly after annealing treatment because the existence of comparatively unstable microstructures. It is suggested that cracking phenomena dominate the damage cause of Si/SiGe SLSs. (C) 2011 Elsevier B. V. All rights reserved.
Nanomechanical properties and fracture toughness of Bi3Se2Te thin films grown using pulsed laser deposition
(2016-10-01)
Phuoc Huu Le
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Luo, Chih-Wei
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Jian, Sheng-Rui
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Lin, Ting-Chun
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Yang, Ping-Feng
Mechanical properties of thermoelectric (TE) materials are crucial for fabricating efficient and endurable TE devices. In this study, polycrystalline Bi3Se2Te thin films are grown on c-plane sapphire substrates at 250 degrees C and helium gas pressure of 6.5 x 10(-1) Torr using pulsed laser deposition (PLD). The structural, compositional, morphological and mechanical properties of Bi3Se2Te thin films are studied. The Bi3Se2Te thin films are highly c-axis oriented structure and exhibit the stoichiometric compositions of Bi3Se2Te phase. The hardness and Young\'s modulus of the Bi3Se2Te thin films are 5.6 +/- 0.2 GPa and 197.2 +/- 5.4 GPa, respectively, which determined by nanoindentation tests with the continuous stiffness measurement (CSM) mode. The true hardness of the Bi3Se2Te thin films is also calculated using the energy principle of nanoindentation contact. The micro-Vicker indentation-induced fracture behavior of the Bi3Se2Te thin films is observed and discussed. (C) 2016 Elsevier B.V. All rights reserved.
Nanomechanical properties of Bi2Te3 thin films by nanoindentation
(2015-01-15)
Tasi, Cheng-Hsun
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Tseng, Yu-Chin
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Jian, Sheng-Rui
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Liao, Ying-Yen
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Lin, Chih-Ming
In this study, the microstructural, morphological and nanomechanical properties of Bi2Te3 thin films are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and nanoindentation techniques. The Bi2Te3 thin films were deposited on c-plane sapphire substrates using pulsed laser deposition (PLD) under the various helium gas pressures. The XRD results indicated that the Bi2Te3 thin films are textured with the c-axis preferentially oriented normal to the films surface. Both the grain size and surface roughness of the Bi2Te3 thin films exhibit an increasing trend with increasing the helium gas pressure. Furthermore, the hardness and Young\'s modulus of the Bi2Te3 thin films are measured by a Berkovich nanoindenter operated with the continuous contact stiffness measurements (CSM) mode were found to range from 2.92 +/- 0.12 to 4.02 +/- 0.14 GPa and from 106.31 +/- 0.63 to 127.46 +/- 9.21 GPa, respectively, when the helium gas pressure was increased from 2 x 10(-5) to 2 x 10(-3) Torr. (C) 2014 Elsevier B.V. All rights reserved.
Nanotribological properties of ALD-processed bilayer TiO2/ZnO films
(2014-12-01)
Wang, Wun-Kai
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Wen, Hua-Chiang
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Cheng, Chun-Hu
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Hung, Ching-Hua
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Chou, Wu-Ching
TiO2/ZnO films grown by atomic layer deposition (ALD) demonstrated nanotribological behaviors using scratch testing. TEM profiles obtained an amorphous structure TiO2 and nanocrystalline structure ZnO, whereas the sample has significant interface between the TiO2/ZnO films. The experimental results show the relative XRD peak intensities are mainly contributed by a wurtzite oxide ZnO structure and no signal from the amorphous TiO2. With respect to tribology, increased friction causes plastic deformation between the TiO2 and ZnO films, in addition to delamination and particle loosening. The plastic deformation caused by adhesion and/or cohesion failure is reflected in the nanoscratch traces. The pile-up events at a loading penetration of 30 nm were measured at 21.8 mu N for RT, 22.4 mu N for 300 degrees C, and 36 mu N for 400 degrees C. In comparison to the other conditions, the TiO2/ZnO films annealed at 400 degrees C exhibited higher scratch resistance and friction with large debris, indicating the wear volume is reduced with increased annealing temperature and loading. (C) 2014 Elsevier Ltd. All rights reserved.
Surface morphological and nanomechanical properties of PLD-derived ZnO thin films
(2008-05-01)
Jian, Sheng-Rui
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Teng, I-Ju
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Yang, Ping-Feng
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Lai, Yi-Shao
;
Lu, Jian-Ming
This study reports the surface roughness and nanomechanical characteristics of ZnO thin films deposited on the various substrates, obtained by means of atomic force microscopy (AFM), nanoindentation and nanoscratch techniques. ZnO thin films are deposited on (a- and c-axis) sapphires and (0001) 6H-SiC substrates by using the pulsed-laser depositions (PLD) system. Continuous stiffness measurements (CSM) technique is used in the nanoindentation tests to determine the hardness and Young's modulus of ZnO thin films. The importance of the ratio (H/E-film) of elastic to plastic deformation during nanoindentation of ZnO thin films on their behaviors in contact-induced damage during fabrication of ZnO-based devices is considered. In addition, the friction coefficient of ZnO thin films is also presented here.