Improving the sensitivity of Raman signal of ZnO thin films deposited on silicon substrate

Hammouda, A.; Canizarès, A.; Simon, Patrick; Boughalout, A.; Kechouane, M.

doi:10.1016/j.vibspec.2012.07.004

Cited by 24 publications

(15 citation statements)

References 19 publications

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“…Prior to polarized Raman measurement on orthochromite single crystals, the polarizer was aligned thanks to a (001) Si wafer. In backscattered configuration, the well‐known T 2g phonon mode at 520 cm −1 gives a maximum intensity for VV configuration along (110) direction of Si wafer …”

Section: Experimental Methodsmentioning

confidence: 99%

“…In backscattered configuration, the well-known T 2g phonon mode at 520 cm −1 gives a maximum intensity for VV configuration along (110) direction of Si wafer. [53] Microcrystals are dispersed on a rotating sample holder. First, an observation by optical microscope is used to select parallel faces to the (X, Y) laboratory plane without wondering its orientation.…”

Section: Experimental Methodsmentioning

confidence: 99%

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Polarized Raman scattering on single crystals of rare earth orthochromite RCrO₃ (R = La, Pr, Nd, and Sm)

Camara

Phuoc

Monot‐Laffez

et al. 2017

J Raman Spectroscopy

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We report on polarized Raman scattering on orthorhombic RCrO3 (R = La, Pr, Nd, and Sm) single crystals at room temperature. The analysis of polarized Raman spectra as a function of polarizer and analyzer angles with respect to crystallographic axes allowed to observe in these flux grown crystals phonon modes that were not detected yet. On the basis of both Raman selection rules and lattice dynamics calculations within density functional perturbations theory framework, the observed Ag, B1g, B2g, and B3g phonon modes were unambiguously assigned. Phonon mode wave number evolutions as a function of orthorhombic distortion, related to rare earth ionic radius, were investigated and highlighted a complex behavior for several low wave number modes allowed crossing. For the modes of same symmetry, a mode mixing behavior is observed, and numerical calculations based on two or three coupling systems were performed to fit experimental data and to extract the coupling constants.

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Section: Experimental Methodsmentioning

confidence: 99%

Section: Experimental Methodsmentioning

confidence: 99%

Polarized Raman scattering on single crystals of rare earth orthochromite RCrO₃ (R = La, Pr, Nd, and Sm)

Camara

Phuoc

Monot‐Laffez

et al. 2017

J Raman Spectroscopy

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“…As noted above, we collected a large number of published Tauc analyses of undoped ZnO that included plots of the absorbance data against the photon energy . This was critical, as our assessment of the application of the Tauc method required the consistent application of a fitting method, as described below.…”

Section: Modelmentioning

confidence: 99%

Evaluation of the Tauc method for optical absorption edge determination: ZnO thin films as a model system

Viezbicke

Patel

Davis

et al. 2015

Phys. Status Solidi B

853

419

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One of the most frequently used methods for characterizing thin films is UV–Vis absorption. The near‐edge region can be fitted to a simple expression in which the intercept gives the band‐gap and the fitting exponent identifies the electronic transition as direct or indirect (see Tauc et al., Phys. Status Solidi 15, 627 (1966); these are often called “Tauc” plots). While the technique is powerful and simple, the accuracy of the fitted band‐gap result is seldom stated or known. We tackle this question by refitting a large number of Tauc plots from the literature and look for trends. Nominally pure zinc oxide (ZnO) was chosen as a material with limited intrinsic deviation from stoichiometry and which has been widely studied. Our examination of the band gap values and their distribution leads to a discussion of some experimental factors that can bias the data and lead to either smaller or larger apparent values than would be expected. Finally, an easily evaluated figure‐of‐merit is defined that may help guide more accurate Tauc fitting. For samples with relatively sharper Tauc plot shapes, the population yields Eg(ZnO) as 3.276 ± 0.033 eV, in good agreement with data for single crystalline material.

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“…Notably, the 3 in. monocrystalline silicon substrate has high Raman cross‐sections, while BPQDs have low optical absorption . In spite of this, three peaks could be clearly observed at 366, 436, and 463 cm −1 , and can be assigned to one out‐of‐plane phonon mode

(A_{g}^{1})

and two in‐plane modes

(B_{2 normalg} normaland A_{g}^{2})

, respectively, confirming the introduction of BPQDs onto the Si substrate …”

Section: Binding Energy (Ev) Of the P4 Molecules On Si(100)‐4 × 2 Andmentioning

confidence: 73%

Epitaxial Growth of Few‐Layer Black Phosphorene Quantum Dots on Si Substrates

Han

et al. 2018

Adv Materials Inter

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antimonene, [10,11] and tellurene, [12] etc. Each invokes different synthesis methods pertaining to their intrinsic structures and properties. Nonetheless, for further practical applications, such as sensors, transistors, lasers, and energy storage, the success of each of those "enchanted" materials depends on the development of quality-controlled, efficient and scalable fabrication methods. Epitaxial growth, e.g., by chemical vapor deposition or molecular beam epitaxy (MBE), has been widely used for two-dimensional (2D) material synthesis, including graphene, silicene, germanene, and MoS 2 . [13][14][15][16] BP nanosheets, as a relatively new member of the 2D family since 2014, have risen to the scientific limelight since its first fabrication by exfoliation. [8,9] BP possesses intriguing properties, such as bandgap tunability by layer thickness, doping, and strain, etc.; in-plane anisotropy, particularly anisotropy in electron conductance; and high carrier mobility. [17,18] However, the fabrication of BP is still limited to poorly controlled mechanical and liquid exfoliations [19][20][21][22][23] and phase transition under harsh conditions. [24,25] Blue phosphorene, another allotrope of BP, has been fabricated using the MBE method. [26,27] There is no report on the synthesis of BP using a bottom-up method, to the best of our knowledge. Particularly, considerable efforts are needed to understand the formation mechanism of the BP, and its stability and sensitivity to substrate for continuous growth.For the first time, we demonstrate the synthesis of black phosphorene quantum dots (BPQDs), as an attempt for above mentioned challenges, i.e., phase transition under the harsh conditions, of epitaxial growth of 2D BP, from white phosphorus directly on 3 in. Si substrates by MBE. Epitaxial BPQDs were grown on fully deoxidized Si(111) at 20 °C and Si(100) covered with native oxide at 15 °C, respectively. The as-grown BPQDs were characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy with BP fingerprint peaks. Uniform and pyramid-shaped BPQDs were obtained on Si(111) substrates, with an average radius of 27.5 ± 5 nm and height of 3.1 ± 0.6 nm. According to the AFM images, BPQDs preferably crystallized at the steps on the Si(111) surface. Comparatively, BPQDs on the nondeoxidized Si(100) substrate without observable surface steps, Elemental 2D materials, such as silicene, germanene, and stanene, are synthesized by molecular beam epitaxy (MBE). However, the epitaxial growth of black phosphorene is challenging to date. Herein, the successful MBE growth of few-layer black phosphorene quantum dots (BPQDs) directly on Si substrates at relatively low temperature using white phosphorus as the precursor is reported. The formation of black phosphorene is confirmed by atomic force microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy, in combination with density functional theory (DFT) calculations. Uniform and pyramid-shaped BPQDs with an average radius of 27.5 ...

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Improving the sensitivity of Raman signal of ZnO thin films deposited on silicon substrate

Cited by 24 publications

References 19 publications

Polarized Raman scattering on single crystals of rare earth orthochromite RCrO₃ (R = La, Pr, Nd, and Sm)

Polarized Raman scattering on single crystals of rare earth orthochromite RCrO₃ (R = La, Pr, Nd, and Sm)

Evaluation of the Tauc method for optical absorption edge determination: ZnO thin films as a model system

Epitaxial Growth of Few‐Layer Black Phosphorene Quantum Dots on Si Substrates

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Improving the sensitivity of Raman signal of ZnO thin films deposited on silicon substrate

Cited by 24 publications

References 19 publications

Polarized Raman scattering on single crystals of rare earth orthochromite RCrO3 (R = La, Pr, Nd, and Sm)

Polarized Raman scattering on single crystals of rare earth orthochromite RCrO3 (R = La, Pr, Nd, and Sm)

Evaluation of the Tauc method for optical absorption edge determination: ZnO thin films as a model system

Epitaxial Growth of Few‐Layer Black Phosphorene Quantum Dots on Si Substrates

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Product

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Polarized Raman scattering on single crystals of rare earth orthochromite RCrO₃ (R = La, Pr, Nd, and Sm)

Polarized Raman scattering on single crystals of rare earth orthochromite RCrO₃ (R = La, Pr, Nd, and Sm)