Browsing by Author "Chen, Yi Cheng"

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GaN growth on Si(111) using simultaneous AlN/alpha-Si(3)N(4) buffer structure
(2008-07-01)
Chang, Jet Rung
;
Yang, Tsung Hsi
;
Ku, Jui Tai
;
Shen, Shih Guo
;
Chen, Yi Cheng
In this study, we examined the growth of a simultaneous AIN/alpha-Si(3)N(4) buffer layer for crack-free GaN growth oil a Si(111) substrate. The compressive stress in the AlN/alpha-Si(3)N(4)/Si(111) structure retards the cracking ill the GaN layer. It is demonstrated that the Al-preseeded layer is a critical factor for accornplishing AlN and the crystalline alpha-Si(3)N(4) layer simultaneously. The effect of Al layer deposition time on the c-axis lattice constants of the subsequent AlN layer, and the effect of the crystalline alpha-Si(3)N(4) layer oil GaN quality were investigated by X-ray diffraction analysis. The 1 : 2 lattice coincidently matches at the alpha-Si(3)N(4)(0001)/Si(111) interface, and the 5 : 2 coincident lattice interface at AlN(0001)/alpha-Si(3)N(4)(0001) reduces the lattice mismatch in the AIN/alpha Si(3)N(4)/Si(111) structure. The 5 : 4 coincident lattice in the AIN/alpha-Si(3)N(4)/Si(111) structure is related to the reduction in the tensile stress in the AIN epilayers. The thickness of crack-free GaN is 2.00 mu m. The full widths at half-maximum (FWHM) of the X-ray rocking curve and neutral-donor-bound exciton (D degrees X) are 1012arcsec and 5.90meV, respectively.
GaN growth on Si(111) using simultaneous AlN/alpha-Si3N4 buffer structure
(2008-07-01)
Chang, Jet Rung
;
Yang, Tsung Hsi
;
Ku, Jui Tai
;
Shen, Shih Guo
;
Chen, Yi Cheng
In this study, we examined the growth of a simultaneous AIN/alpha-Si3N4 buffer layer for crack-free GaN growth oil a Si(111) substrate. The compressive stress in the AlN/alpha-Si3N4/Si(111) structure retards the cracking ill the GaN layer. It is demonstrated that the Al-preseeded layer is a critical factor for accornplishing AlN and the crystalline alpha-Si3N4 layer simultaneously. The effect of Al layer deposition time on the c-axis lattice constants of the subsequent AlN layer, and the effect of the crystalline alpha-Si3N4 layer oil GaN quality were investigated by X-ray diffraction analysis. The 1 : 2 lattice coincidently matches at the alpha-Si3N4(0001)/Si(111) interface, and the 5 : 2 coincident lattice interface at AlN(0001)/alpha-Si3N4(0001) reduces the lattice mismatch in the AIN/alpha Si3N4/Si(111) structure. The 5 : 4 coincident lattice in the AIN/alpha-Si3N4/Si(111) structure is related to the reduction in the tensile stress in the AIN epilayers. The thickness of crack-free GaN is 2.00 mu m. The full widths at half-maximum (FWHM) of the X-ray rocking curve and neutral-donor-bound exciton (D degrees X) are 1012arcsec and 5.90meV, respectively.
Nanochip-Induced Epithelial-to-Mesenchymal Transition: Impact of Physical Microenvironment on Cancer Metastasis
(2018-04-11)
Dhawan, Udesh
;
Sue, Ming-Wen
;
Lan, Kuan-Chun
;
Buddhakosai, Waradee
;
Pao Hui Huang
Epithelial-to-mesenchymal transition (EMT) is a highly orchestrated process motivated by the nature of physical and chemical compositions of the tumor microenvironment (TME). The role of the physical framework of the TME in guiding cells toward EMT is poorly understood. To investigate this, breast cancer MDA-MB-231 and MCF-7 cells were cultured on nanochips comprising tantalum oxide nanodots ranging in diameter from 10 to 200 nm, fabricated through electrochemical approach and collectively referred to as artificial microenvironments. The 100 and 200 nm nanochips induced the cells to adopt an elongated or spindle-shaped morphology. The key EMT genes, E-cadherin, N-cadherin, and vimentin, displayed the spatial control exhibited by the artificial microenvironments. The E-cadherin gene expression was attenuated, whereas those of N-cadherin and vimentin were amplified by 100 and 200 rim nanochips, indicating the induction of EMT. Transcription factors, snail and twist, were identified for modulating the EMT genes in the cells on these artificial microenvironments. Localization of EMT proteins observed through immunostaining indicated the loss of cell cell junctions on 100 and 200 rim nanochips, confirming the EMT induction. Thus, by utilizing an in vitro approach, we demonstrate how the physical framework of the TME may possibly trigger or assist in inducing EMT in vivo. Applications in the fields of drug discovery, biomedical engineering, and cancer research are expected.