Browsing by Author "Yen, Tzu-Chun"

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2H-Silicon Carbide Epitaxial Growth on c-Plane Sapphire Substrate Using an AlN Buffer Layer and Effects of Surface Pre-Treatments
(2015-05-01)
Luong, Tien-Tung
;
Binh Tinh Tran
;
Ho, Yen-Teng
;
Wei, Ting-Wei
;
Wu, Yue-Han
The effects of surface pre-treatments and the role of an AN buffer layer for 2H-SiC growth on c-plane sapphire substrates by thermal CVD are investigated. While the crystallinity of SiC directly grown on sapphire substrate always degrades with a hydrogen pre-treatment but improves by optimizing carbonization, the crystallinity of SiC grown on sapphire substrate using an AN buffer grown by MOCVD improves with sufficient time of exposure to the H pre-treatment but always deteriorates with carbonization. Detailed microstructural analysis by phi-scan x-ray diffraction reveals that SiC film grown on sapphire substrate consists of crystalline domains with two different crystallographic orientations which are rotated relative to each other along the [111] axis by 60 degrees. A highly oriented hexagonal 2H-SiC film is obtained on low-cost c-plane sapphire substrate by using an AN buffer. 2H-SiC is unambiguously determined not only by phi-scan x-ray diffraction but also by high-resolution transmission electron microscopy. The growth relationship between 2H-SiC and 2H-AlN are coherent due to the favorable bonding of C and Al between SiC and AlN.
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 nonpolar (13(4)over-bar0) ZnO epitaxial film grown on (114) LaAlO3 substrate
(2014-03-01)
Yen, Tzu-Chun
;
Wang, Wei-Lin
;
Peng, Chun-Yen
;
Tian, Jr-Sheng
;
Ho, Yen-Teng
The defects in (13 (4) over bar0)ZnO epitaxial film grown on (114)LaAlO3 (LAO) have been systematically investigated by using transmission electron microscopy. At the ZnO/LAO interface, the Burgers vectors of misfit dislocations are identified to be 1/3[(1) over bar2 (1) over bar0] and 1/2[0001]. Threading dislocations with the Burgers vectors of 1/3 < 11 (2) over bar0 > and < 0001 > are distributed on the basal plane. In (13 (4) over bar0)ZnO film, the predominant planar defects are basal stacking faults (BSFs) with 1/6 < 20 (2) over bar3 > displacement vectors. The densities of dislocations and BSFs are about 3.8 x 10(10) cm(-2) and 3.1 x 10(5) cm(-1), respectively. (C) 2014 American Vacuum Society.
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.
Layered MoS2 grown on c-sapphire by pulsed laser deposition
(2015-03-01)
Ho, Yen-Teng
;
Ma, Chun-Hao
;
Luong, Tien-Tung
;
Wei, Lin-Lung
;
Yen, Tzu-Chun
Layered growth of molybdenum disulphide (MoS2) was successfully achieved by pulsed laser deposition (PLD) method on c-plane sapphire substrate. Growth of monolayer to a few monolayer MoS2, dependent on the pulsed number of excimer laser in PLD is demonstrated, indicating the promising controllability of layer growth. Among the samples with various pulse number deposition, the frequency difference (A1gE12g) in Raman analysis of the 70 pulse sample is estimated as 20.11 cm(1), suggesting a monolayer MoS2 was obtained. Two-dimensional (2D) layer growth of MoS2 is confirmed by the streaky reflection high energy electron diffraction (RHEED) patterns during growth and the cross-sectional view of transmission electron microscopy (TEM). The in-plane relationship, (0006) sapphire//(0002) MoS2 and inline image sapphire//inline imageMoS(2) is determined. The results imply that PLD is suitable for layered MoS2 growth. Additionally, the oxide states of Mo 3d core level spectra of PLD grown MoS2, analysed by X-ray photoelectron spectroscopy (XPS), can be effectively reduced by adopting a post sulfurization process. (C) 2015 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim
POST SULFURIZATION EFFECT ON THE MOS2 GROWN BY PULSED LASER DEPOSITION
(2016)
Ho, Yen-Teng
;
Yen, Tzu-Chun
;
Luong, Tien-Tung
;
Wei, Lin-Lung
;
Tu, Yung-Yi
Two inches size with high quality layered growth of MoS2 was achieved by PLD on c-plane sapphire substrate. 2-3 monolayer MoS2 was obtained within 2 inches wafer estimated from Raman analysis and confirmed by cross-sectional view of TEM. Additionally, the oxide states of Mo 3d core level spectra of MoS2, analyzed by XPS, can be effectively reduced by adopting a post sulfurization process in H2S. The post process also improve the photoluminescence (PL) of MoS2 as well as the electrical characteristic of MoS2 FET due to elimination the Mo oxide in the grown film.
Single domain non-polar (12(3)over-bar0)ZnO epitaxy on (118)LaAlO3 by pulsed laser deposition
(2016-11-01)
Yen, Tzu-Chun
;
Ho, Yen-Teng
;
Peng, Chun-Yen
;
Tian, Jr-Sheng
;
Shih, Yi-Sen
An unconventional non-polar (12 (3) over bar0)ZnO epitaxial film is grown on (118)LaAlO3(LAO) substrate by pulsed laser deposition. X-ray diffraction pole figures and transmission electron microscopy show that the crystal orientation relationships between non-polar (1230)ZnO and (118)LAO substrate are (0001)ZnO // (110)LAO and (1120)ZnO // (001)LAO. The Raman spectrum with a significant E2 peaked at 439 cm(-1) clearly indicates the formation of non-polar ZnO film. Photoluminescence measurement of the non-polar ZnO film shows a strong near band-edge emission located at 3.3 eV with negligible green-yellow emission. (C) 2016 Elsevier B.V. All rights reserved.
Single domain non-polar (12(3)over-bar0)ZnO epitaxy on (118)LaAlO3 by pulsed laser deposition
(2016-11-01)
Yen, Tzu-Chun
;
Ho, Yen-Teng
;
Peng, Chun-Yen
;
Tian, Jr-Sheng
;
Shih, Yi-Sen
An unconventional non-polar (12 (3) over bar0)ZnO epitaxial film is grown on (118)LaAlO3(LAO) substrate by pulsed laser deposition. X-ray diffraction pole figures and transmission electron microscopy show that the crystal orientation relationships between non-polar (1230)ZnO and (118)LAO substrate are (0001)ZnO // (110)LAO and (1120)ZnO // (001)LAO. The Raman spectrum with a significant E2 peaked at 439 cm(-1) clearly indicates the formation of non-polar ZnO film. Photoluminescence measurement of the non-polar ZnO film shows a strong near band-edge emission located at 3.3 eV with negligible green-yellow emission. (C) 2016 Elsevier B.V. All rights reserved.
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.
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.
The role of the interface structure on the growth of nonpolar (10(1)over-bar0) and semipolar (11(2)over-bar(2)over-bar) ZnO on (112) LaAlO3 substrates
(2013-10-15)
Tian, Jr-Sheng
;
Wu, Yue-Han
;
Wang, Wei-Lin
;
Yen, Tzu-Chun
;
Ho, Yen-Teng
Growth of nonpolar (10 (1) over bar0) and semipolar (11 (2) over bar(2) over bar) ZnO on (112) LaAlO3 (LAO) substrates can be obtained by annealing the substrate surface in vacuum and oxygen ambient conditions prior to ZnO deposition, respectively. We investigated the origin of the two different growth relationships by inspecting their interface in atomic scale using high angle annular dark field scanning transmission electron microscopy. (10 (1) over bar0) ZnO was grown on flat (112)(LAO) surface due to the similar atomic configurations and small lattice mismatch between them at the interface, and (11 (2) over bar(2) over bar) ZnO was grown on a faceted surface with (001)(LAO) and (110)(LAO) facets on which accommodation growth of both (11 (2) over bar0) ZnO and (000 (1) over bar) ZnO are consistent with [1 (1) over bar 00](ZNO)//[1 (1) over bar0](LAO). (C) 2013 Elsevier B.V. All rights reserved.