Browsing by Author "Do, Hien"

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Atomically resolved interface structure between epitaxial TiN film and MgO substrate
(2016-11-01)
Wei, Lin-Lung
;
Yen, Tzu-Chun
;
Do, Hien
;
Chang, Li
;
材料科學與工程學系
In this study, we used a high quality epitaxial TiN thin film grown on MgO (001) substrate for the investigation of the TiN/MgO interface structure which was characterized with scanning transmission electron microscopy (STEM) at atomic resolution. Analyses of high angle annular dark-field and annular bright-field STEM image contrast with X-ray energy dispersive spectroscopy maps show that a 2-4 nm diffuse interlayer of mixed compositions exists coherently between TiN and MgO with the same structure and across the interface the ionic bonding sequences are maintained without any interruption. (C) 2016 Elsevier B.V. All rights reserved.
Atomically resolved interface structure between epitaxial TiN film and MgO substrate
(2016-11-01)
Wei, Lin-Lung
;
Yen, Tzu-Chun
;
Do, Hien
;
Chang, Li
;
材料科學與工程學系
In this study, we used a high quality epitaxial TiN thin film grown on MgO (001) substrate for the investigation of the TiN/MgO interface structure which was characterized with scanning transmission electron microscopy (STEM) at atomic resolution. Analyses of high angle annular dark-field and annular bright-field STEM image contrast with X-ray energy dispersive spectroscopy maps show that a 2-4 nm diffuse interlayer of mixed compositions exists coherently between TiN and MgO with the same structure and across the interface the ionic bonding sequences are maintained without any interruption. (C) 2016 Elsevier B.V. All rights reserved.
Defects in semipolar (11(2)over-bar(2)over-bar) ZnO grown on (112) LaAlO3/(La, Sr) (Al, Ta)O-3 substrate by pulsed laser deposition
(2013-03-27)
Tian, Jr-Sheng
;
Wu, Yue-Han
;
Peng, Chun-Yen
;
Chiu, Kun-An
;
Shih, Yi-Sen
The microstructure of semipolar (11 (2) over bar(2) over bar) ZnO deposited on (112) LaAlO3/(La, Sr) (Al, Ta)O-3 was investigated by transmission electron microscopy. The ZnO shows an in-plane epitaxial relationship of [11 (2) over bar3](ZnO) parallel to [11 (1) over bar](LAO/LSAT) with oxygen-face sense polarity. The misfit strain along [11 (2) over bar3](ZnO) and [1 (1) over bar 00](ZnO) is relieved through the formation of misfit dislocations with the Burgers vectors b = 1/6[11 (2) over bar3](ZnO) and b = 1/3 < 1 (2) over bar 10 >(ZnO), respectively. The line defects in the semipolar ZnO are predominantly perfect dislocations, and the dislocation density decreases with increasing ZnO thickness as a result of dislocation reactions. Planar defects were observed to lie in the M-plane and extend along < 0001 >, whereas basal stacking faults were rarely found.
Epitaxial growth of titanium oxycarbide on MgO (001) substrates by pulsed laser deposition
(2011-01-15)
Do, Hien
;
Yen, Tzu-Chun
;
Tian, Chih-Sheng
;
Wu, Yue-Han
;
Chang, Li
Epitaxial TiC(x)O(y) thin films were grown on MgO (0 0 1) substrates by using pulsed laser deposition method. High-resolution X-ray diffraction and transmission electron microscopy were used to examine crystallinity and microstructure of epitaxial TiC(x)O(y) film on MgO. The chemical composition of the film is determined to be x similar to 0.47 and y similar to 0.69 by X-ray photoelectron spectroscopy. Atomic force microscopy revealed that the surface of TiC(x)O(y) film is very smooth with roughness of 0.18 nm. The resistivity of the TiC(x)O(y) film measured by four-point-probe method was about 137 mu Omega cm. (C) 2010 Elsevier B.V. All rights reserved.
Reactive sputtering for highly oriented HfN film growth on Si (100) substrate
(2019-11-15)
Fang, Yu-Siang
;
Chiu, Kun-An
;
Do, Hien
;
Chang, Li
;
材料科學與工程學系
Highly oriented cubic (100) HfN films were grown on Si (100) substrates by direct current magnetron reactive sputtering of a metallic Hf target in an Ar/N-2 gas environment. The influence of N-2 flow ratio on the (100) preferred orientation and crystallinity of the HfN films is investigated. X-ray diffraction shows that not only HEN but also orthorhombic HfSi2 forms in the sputtered films. Increasing the N-2 flow ratio is unfavorable for the formation of HfSi2 while the deposition rate of HfN is decreased. X-ray diffraction and cross-sectional scanning transmission electron microscopy (STEM) reveal that epitaxial orthorhombic HfSi2 can form on the Si substrate, and (100) HfN is in epitaxy with the epitaxial HfSi2. As a result, a (100) oriented HfN film can grow on Si. The epitaxial relationships are shown to be HfN (100)[01 (1) over bar] // HfSi2 (020)[001] // Si (100)[01 (1) over bar] and HfN (100)[01 (1) over bar] // HfSi2 (020)[100] // Si (100)[01 (1) over bar]. Atomically resolved STEM images also show the bonding characteristics across the HfN/HfSi2 and HfSi2/Si interfaces.
Stability and etching of titanium oxynitride films in hydrogen microwave plasma
(2013-07-01)
Do, Hien
;
Yen, Tzu-Chun
;
Chang, Li
;
材料科學與工程學系
;
Department of Materials Science and Engineering
Epitaxial titanium oxynitride (TiNO) films deposited on MgO by pulsed laser deposition were treated in hydrogen microwave plasma. Scanning electron microscopy and x-ray photoelectron spectroscopy were used to examine the stability and etching of TiNO which strongly depended on hydrogen gas pressure. TiNO was very chemically stable and remained with good crystallinity under hydrogen pressure below 5300 Pa. With increase of pressure, it may lead to the formation of etch pits in inverse pyramid shape. The etch mechanism as well as the effects of gas pressure and etching time are also presented. (C) 2013 American Vacuum Society.
Structural and nanoindentation studies of epitaxial titanium oxynitride (001) films grown on MgO(001) substrate
(2014-07-25)
Do, Hien
;
Van-Truong Dai
;
Tian, Jr-Sheng
;
Yen, Tzu-Chun
;
Chang, Li
We investigate the effect of chemical composition and residual stress on the mechanical properties of high-quality epitaxial TiNxOy films deposited on MgO(001) substrates by using nanoindentation. The lattice parameters and residual strain/stress of TiNxOy films decrease as oxygen concentration increases. Hardness and Young\'s modulus determined by nanoindentation are about 17-26 GPa and 355-430 GPa, respectively, which vary with chemical composition and residual stress. (C) 2014 Elsevier B.V. All rights reserved.
Structural and photoluminescence investigation on the hot-wire assisted plasma enhanced chemical vapor deposition growth silicon nanowires
(2012-06-01)
Chong, Su Kong
;
Goh, Boon Tong
;
Wong, Yuen-Yee
;
Nguyen, Hong-Quan
;
Do, Hien
High density of silicon nanowires (SiNWs) were synthesized by a hot-wire assisted plasma enhanced chemical vapor deposition technique. The structural and optical properties of the as-grown SiNWs prepared at different rf power of 40 and 80 W were analyzed in this study. The SiNWs prepared at rf power of 40 W exhibited highly crystalline structure with a high crystal volume fraction. X-C of similar to 82% and are surrounded by a thin layer of SiOx. The NWs show high absorption in the high energy region (E > 1.8 eV) and strong photoluminescence at 1.73 to 2.05 eV (red-orange region) with a weak shoulder at 1.65 to 1.73 eV (near IR region). An increase in rf power to 80 W reduced the X-C to similar to 65% and led to the formation of nanocrystalline Si structures with a crystallite size of < 4 nm within the SiNWs. These NWs are covered by a mixture of uncatalyzed amorphous Si layer. The SiNWs prepared at 80 W exhibited a high optical absorption ability above 99% in the broadband range between 220 and similar to 1500 nm and red emission between 1.65 and 1.95 eV. The interesting light absorption and photoluminescence properties from both SiNWs are discussed in the text. (C) 2012 Elsevier B.V. All rights reserved.
Structure and property of epitaxial titanium oxynitride grown on MgO(001) substrate by pulsed laser deposition
(2013-01-15)
Do, Hien
;
Wu, Yue-Han
;
Van-Truong Dai
;
Peng, Chun-Yen
;
Yen, Tzu-Chun
High-quality epitaxial TiNxOy, films with different oxygen content were deposited on MgO(001) substrates by pulsed laser deposition method. The chemical composition of the deposited films was determined by X-ray photoelectron spectroscopy. X-ray diffraction results showed that the TiNxOy films are heteroepitaxially grown on MgO with good crystallinity and their lattice parameters decrease with increased oxygen concentration. Transmission electron microscopy analyses showed that TiNxOy films contain a low density of dislocations. Atomic force microscopy revealed very smooth surfaces of TiNxOy films with roughness of 026-0.29 nm. The resistivity of TiNxOy, films determined by Hall measurement was about 28-33 mu Omega cm. Nanoindentation measurements showed the film hardness and Young's modulus of about 23-26 GPa and 400-430 GPa, respectively. (C) 2012 Elsevier B.V. All rights reserved.