Raman characterization of electronic properties of self-assembled GaN nanorods grown by plasma-assisted molecular-beam epitaxy

Wang, D.; Tin, C. C.; Williams, John R.; Park, M.; Park, Y. S.; Park, C. M.; Kang, Tae Won; Yang, Woochul

doi:10.1063/1.2146066

Cited by 22 publications

(6 citation statements)

References 21 publications

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“…Thus, the E 1 ͑LO͒ mode at 740 cm −1 systematically appears in nominal backscattering along the c axis in the spectra of GaN nanocolumns. 25,26 Also, the Raman spectra re-ported in Fig. 3 of Ref.…”

Section: Resultsmentioning

confidence: 99%

Phonon-plasmon coupling in electron surface accumulation layers in InN nanocolumns

et al. 2007

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Raman measurements in high quality InN nanocolumns display a coupled LO phonon-plasmon mode together with uncoupled phonons. The coupled mode is attributed to the spontaneous accumulation of electrons on the lateral surfaces of the nanocolumns. For increasing growth temperature, the electron density decreases as the growth rate increases. The present results indicate that electron accumulation layers do not only form on polar surfaces of InN but also occur on nonpolar ones. According to recent calculations, we attribute the electron surface accumulation to the temperature dependent In-rich surface reconstruction on the nanocolumn sidewalls.

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Section: Resultsmentioning

confidence: 99%

Phonon-plasmon coupling in electron surface accumulation layers in InN nanocolumns

et al. 2007

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“…2 optical modes are predicted at the point of the Brillouin zone of hexagonal GaN [20]. Based on the Raman selection rules, only the E low 2 , E high 2and A 1 (LO) modes can be observed with the z(−, −)z scattering geometry in this experiment[21]. As shown in figure 3, the Raman signal near 733 cm −1 corresponds to the A 1 (LO) mode and the broadened line located near 568 cm −1 corresponds to the E high 2 mode of GaN.…”

mentioning

confidence: 94%

Built-in surface electric field, piezoelectricity and photoelastic effect in GaN nanorods for nanophotonic devices

Chen

Cheng

et al. 2008

Nanotechnology

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Novel behaviors arising from the coupling between the built-in surface electric field, piezoelectricity, electron-hole pairs and external light beam were observed in GaN nanorods. An increase in the optical excitation density resulted in a blueshift in the photoluminescence spectra and a redshift in the frequency of the GaN A(1)(LO) phonon. The underlying mechanism was attributed to the screening of the built-in surface electric field by photoexcited carriers and, through the converse piezoelectric effect, a reduction in the internal strain. The existence of the built-in surface electric field in GaN nanorods was confirmed by scanning Kelvin probe microscopy. Our results firmly establish the existence of the photoelastic effect in GaN nanorods. In addition to underpinning the principle for applications in nanophotonic devices, this discovery also draws attention to the novel effects arising from the inherent large surface-to-volume ratio of nanostructures, which is possibly applicable to many other nanomaterials.

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“…15 Previously, the electronic parameters of GaN thin film and nanorods have been determined by using Raman spectroscopy. 16,17 However, this method has not been applied in determining the electronic parameters of ZnO nanostructures. Therefore, in this work, we have collected LPP modes of ZnO nanorods and determined the free a͒ Author to whom correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

Raman analysis of longitudinal optical phonon-plasmon coupled modes of aligned ZnO nanorods

Cheng

Tzeng²,

et al. 2009

Journal of Applied Physics

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The electronic properties of vertically aligned ZnO nanorods have been investigated using micro-Raman spectroscopy. The concentration and mobility of the charge carriers were determined via Raman line shape analysis using longitudinal-optical-phonon-plasmon coupled mode. The local laser heating and the stress effects have been considered when analyzing the Raman spectra. The mobility and carrier concentration of the aligned ZnO nanorods are 84.8 cm 2 / V s and 3.8 ϫ 10 17 cm −3 , respectively. As a comparison, the mobility and carrier concentration of the undoped bulk ZnO were also obtained from the Raman line shape analysis. The mobility of the aligned ZnO nanorods is about 20% lower than that of the undoped bulk ZnO, which can be attributed to enhanced surface scattering due to the reduction in dimension.

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Raman characterization of electronic properties of self-assembled GaN nanorods grown by plasma-assisted molecular-beam epitaxy

Cited by 22 publications

References 21 publications

Phonon-plasmon coupling in electron surface accumulation layers in InN nanocolumns

Phonon-plasmon coupling in electron surface accumulation layers in InN nanocolumns

Built-in surface electric field, piezoelectricity and photoelastic effect in GaN nanorods for nanophotonic devices

Raman analysis of longitudinal optical phonon-plasmon coupled modes of aligned ZnO nanorods

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