GaAs nanocrystals: Structure and vibrational properties

Nayak, J.; Sahu, S.N.; Nozaki, Satoshi

doi:10.1016/j.apsusc.2005.04.031

Cited by 10 publications

(6 citation statements)

References 23 publications

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“…The new peak has been assigned to a point defect such as an arsenic vacancy. 99 The particle size distribution (Gaussian) has also been taken into account while fitting the calculated line shape to the Raman spectra of GaAs nanostructures. 100 Temperature dependence of the Raman spectra of nanocrystalline ZnSe has been analysed on the basis of the anharmonicity of the LO phonons.…”

Section: Oxides and Compoundsmentioning

confidence: 99%

“…The effect of disorder has been discussed in other systems also recently. 97 Several GaAs nanostructures have been created using electrochemical 98,99 and photochemical methods. 100 An orthorhombic structure of a nano-GaAs film on an indium-tin oxide substrate, inferred from TEM, 98 exhibits a new Raman peak at 250 cm 1 , in addition to the TO and LO phonons.…”

Section: Oxides and Compoundsmentioning

confidence: 99%

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Raman spectroscopy of optical phonon confinement in nanostructured materials

Arora

Rajalakshmi

Ravindran

et al. 2007

J Raman Spectroscopy

349

290

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If the medium surrounding a nano-grain does not support the vibrational wavenumbers of a material, the optical and acoustic phonons get confined within the grain of the nanostructured material. This leads to interesting changes in the vibrational spectrum of the nanostructured material as compared to that of the bulk. Absence of periodicity beyond the particle dimension relaxes the zone-centre optical phonon selection rule, causing the Raman spectrum to have contributions also from phonons away from the Brillouin-zone centre. Theoretical models and calculations suggest that the confinement results in asymmetric broadening and shift of the optical phonon Raman line, the magnitude of which depends on the widths of the corresponding phonon dispersion curves. This has been confirmed for zinc oxide nanoparticles. Microscopic lattice dynamical calculations of the phonon amplitude and Raman spectra using the bond-polarizability model suggest a power-law dependence of the peak-shift on the particle size. This article reviews recent results on the Raman spectroscopic investigations of optical phonon confinement in several nanocrystalline semiconductor and ceramic/dielectric materials, including those in selenium, cadmium sulphide, zinc oxide, thorium oxide, and nano-diamond. Resonance Raman scattering from confined optical phonons is also discussed.

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Section: Oxides and Compoundsmentioning

confidence: 99%

Section: Oxides and Compoundsmentioning

confidence: 99%

Raman spectroscopy of optical phonon confinement in nanostructured materials

Arora

Rajalakshmi

Ravindran

et al. 2007

J Raman Spectroscopy

349

290

View full text Add to dashboard Cite

show abstract

“…The Raman spectrum obtained from (As/Ga) sample annealed at 800 °C reveals two peaks at 269 and 290.4 cm -1 . These two peaks are associated to TO and LO GaAs phonon modes [18]. On the other hand, the GaAs phonon modes were not detected in (As/Ga) samples annealed at temperatures below 800 °C.…”

Section: Results and Discussion 31 Binary Ncs Formation In Simentioning

confidence: 86%

Ion beam synthesis of embedded III‐As nanocrystals in silicon substrate

Khelifi

Frégnaux

Gall

et al. 2014

Phys. Status Solidi C

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Our goal is to use the versatility of ion beam synthesis to grow nanocrystals of InxGa1‐xAs alloys embedded in a silicon substrate. We study, first, the annealing conditions necessary to grow well defined InAs and GaAs binary nanocrystals. High dose of As, Ga and In is implanted, respectively, at 130, 130 and 180 keV to have overlapping as‐implanted profiles. The nanocrystals growth is then achieved by rapid thermal annealing at various temperatures between 650 and 800 °C for 1 min under an argon gas flow. Rutherford backscattering spectroscopy profiles show that no significant impurity out‐diffusion occurs below 800 °C for both systems. In and As thermal redistributions lead to superposed profiles. Raman spectroscopy measurements prove that InAs nanocrystals are formed above 650 °C, while 800 °C annealing is necessary to obtain GaAs nanocrystals and show that these thermal budgets are enough to fully recrystallize the implanted layer. Grazing incidence X‐ray diffraction patterns exhibit clearly InAs and GaAs related peaks. These results prove that GaAs and InAs nanocrystals can be grown in a common temperature range (700‐800 °C), opening the route to the growth of ternary InxGa1‐xAs alloys in the same conditions. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…Beam was focused by a 100 mm focal length f-theta lens to spot a diameter of 70 mm on the target. The target used in the experiment was a polished (1 0 0) single-crystal 8 Â 8 mm 2 GaAs wafer with a thickness of about 0.6 mm. The GaAs target was placed at the bottom of a glass vessel containing 10 mL distilled water.…”

Section: Methodsmentioning

confidence: 99%

“…Among different semiconductors, the III-V class like gallium arsenide (GaAs) has acquired a great importance due to its wide range of applicability in device physics. For many years, GaAs -having direct bulk band gap 1.42 eV and Bohr exciton diameter 19 nm -has been the most suitable candidate for fabrication of photovoltaic devices, hetero structures, semiconductor lasers and light emitting diodes [2,3]. This motivates one to proceed with the fabrication and characterisation of GaAs nanocrystals (NCs).…”

Section: Introductionmentioning

confidence: 99%

Optimisation of GaAs nanocrystals synthesis by laser ablation in water

Sharifi

Dorranian

Torkamany

2013

Journal of Experimental Nanoscience

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Laser ablation of a gallium arsenide (GaAs) wafer immersed in distilled water was carried out using the fundamental wavelength of a high frequency Nd:YAG laser with 240 ns pulse duration. Rate of nanoparticles generation through laser ablation for various amounts of laser pulse energies (0.4-0.94 mJ) and repetition rates (400-2000 Hz) were studied and a maximum ablation rate of 19.6 mgr/s was obtained. Formation of the pure GaAs nanocrystals (NCs) is confirmed using TEM micrograph and X-ray diffraction analysis. Band-gap energy of generated GaAs NCs is calculated by Tauc method to be between 2.48 and 2.60 eV which is larger than the band-gap energy of bulk GaAs. The band-gap energy of NCs is increased by increasing the energy of laser pulses and is decreased by increasing the pulse repetition rate.

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GaAs nanocrystals: Structure and vibrational properties

Cited by 10 publications

References 23 publications

Raman spectroscopy of optical phonon confinement in nanostructured materials

Raman spectroscopy of optical phonon confinement in nanostructured materials

Ion beam synthesis of embedded III‐As nanocrystals in silicon substrate

Optimisation of GaAs nanocrystals synthesis by laser ablation in water

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