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Photoemission oscillation in epitaxially grown van der Waals β-In2Se3/WS2 heterobilayer bubbles 下载免费PDF全文
Thin films of millimeter-scale continuous monolayer WS2 have been grown on SiO2/Si substrate, followed by the deposition of β-In2Se3 crystals on monolayer WS2 to prepare In2Se3/WS2 van de Waals heterostructures by a two-step chemical vapor deposition (CVD) method. After the growth of In2Se3 at elevated temperatures, high densities of In2Se3/WS2 heterostructure bubbles with monolayer to multilayer β-In2Se3 crystals atop are observed. Fluorescence of the resultant β-In2Se3/WS2 heterostructure is greatly enhanced in intensity upon the formation of bubbles, which are evidenced by the Newton's rings in optical image owing to constructive and destructive interference. In photoluminescence (PL) mapping images of monolayer β-In2Se3/monolayer WS2 heterobilayer bubble, significant oscillatory behavior of emission intensity is demonstrated due to constructive and destructive interference. However, oscillatory behaviors of peak position are also observed and come from a local heating effect induced by an excitation laser beam. The oscillatory mechanism of PL is further verified by changing the exterior pressure of bubbles placed in a home-made vacuum chamber. In addition, redshifted in peak position and broadening in peak width are observed due to strain effect during decreasing the exterior pressure of bubbles. 相似文献
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Influence of oxygen on the growth of cubic boron nitride thin films by plasma-enhanced chemical vapour deposition 下载免费PDF全文
Cubic boron nitride thin films were deposited on silicon
substrates by low-pressure inductively coupled plasma-enhanced
chemical vapour deposition. It was found that the introduction of
O2 into the deposition system suppresses both nucleation and
growth of cubic boron nitride. At a B2H6 concentration of
2.5\% during film deposition, the critical O2 concentration
allowed for the nucleation of cubic boron nitride was found to be
less than 1.4\%, while that for the growth of cubic boron nitride
was higher than 2.1\%. Moreover, the infrared absorption peak
observed at around 1230--1280~cm-1, frequently detected for
cubic boron nitride films prepared using non-ultrahigh vacuum
systems, appears to be due to the absorption of boron oxide, a
contaminant formed as a result of the oxygen impurity. Therefore,
the existence of trace oxygen contamination in boron nitride films
can be evaluated qualitatively by this infrared absorption peak. 相似文献
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This paper investigates the procedure of cubic boron nitride (cBN) thin film delamination by Fourier-transform infrared (IR) spectroscopy. It finds that the apparent IR absorption peak area near 1380cm^-1 and 1073 cm^-1 attributed to the B-N stretching vibration of sp2-bonded BN and the transverse optical phonon of cBN, respectively, increased up to 195% and 175% of the original peak area after film delamination induced compressive stress relaxation. The increase of IR absorption of sp2-bonded BN is found to be non-linear and hysteretic to film delamination, which suggests that the relaxation of the turbostratic BN (tBN) layer from the compressed condition is also hysteretic to film delamination. Moreover, cross-sectional transmission electron microscopic observations revealed that cBN film delamination is possible from near the aBN(amorphous BN)/tBN interface at least for films prepared by plasma-enhanced chemical vapour deposition. 相似文献
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