Phonon shifts in ion bombarded GaAs: Raman measurements

Burns, Gerald; Dacol, F. H.; Wie, C. R.; Burstein, E.; Cardona, M.

doi:10.1016/0038-1098(87)91096-9

Cited by 71 publications

(30 citation statements)

References 25 publications

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“…Such defects were shown to give rise to a sizeable reduction of ⍀ GaAs 2 in disordered GaAs. 14 Following the arguments of Burns et al, 14 we find that a ratio of vacancies ͑antisites͒ to atoms of ϳ0.5% ͑ϳ0.3% ͒ in the sample with y = 1.5% may account for our Raman data. With regard to this, one should keep in mind that dilute nitrides contain a high density of defects, mainly N interstitials, Ga vacancies, and N clusters, which are responsible for the low luminescence efficiency of the as-grown materials.…”

Section: Gaas-like To-lo Splittingsupporting

confidence: 68%

“…7,13 With regard to this, it should be mentioned that previous works have shown that the SCM fails to explain simultaneously the frequency behavior of the TO and LO peaks in disordered GaAs. 14,15 Despite its usefulness to account for the phonon shifts in microcrystals, the SCM has several limitations. First, the SCM predicts larger confinement-induced frequency shifts for the TO mode than for the LO mode of GaAs, as deduced from Raman scattering results on GaAs/ AlAs superlattices.…”

Section: Gaas-like To-lo Splittingmentioning

confidence: 99%

“…First, the SCM predicts larger confinement-induced frequency shifts for the TO mode than for the LO mode of GaAs, as deduced from Raman scattering results on GaAs/ AlAs superlattices. 14,16 However, such TO phonon shifts are not observed experimentally in disordered GaAs. 14,17 In addition, to fit the Raman data with the SCM in disordered GaAs one has to arbitrarily change the phonon amplitude at the boundary of the microcrystalline regions from 1 / e to exp͑−4 2 ͒.…”

Section: Gaas-like To-lo Splittingmentioning

confidence: 99%

“…14,16 However, such TO phonon shifts are not observed experimentally in disordered GaAs. 14,17 In addition, to fit the Raman data with the SCM in disordered GaAs one has to arbitrarily change the phonon amplitude at the boundary of the microcrystalline regions from 1 / e to exp͑−4 2 ͒. 15 An alternative account of the shifts and broadening of the optical phonon Raman peaks of disordered GaAs was provided by Burns et al, who considered both strain effects and a change in the TO-LO splitting due to the presence of vacancies, antisites, and interstitials in order to explain their results in ion-bombarded GaAs.…”

Section: Gaas-like To-lo Splittingmentioning

confidence: 99%

“…15 An alternative account of the shifts and broadening of the optical phonon Raman peaks of disordered GaAs was provided by Burns et al, who considered both strain effects and a change in the TO-LO splitting due to the presence of vacancies, antisites, and interstitials in order to explain their results in ion-bombarded GaAs. 14 The long-range effects associated with LO phonons ͑i.e., the macroscopic ionic polarization͒ may also play an important role in the behavior of the GaAslike LO branch of Ga͑As,N͒.…”

Section: Gaas-like To-lo Splittingmentioning

confidence: 99%

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Optical phonon behavior in strain-free dilute Ga(As,N) studied by Raman scattering

Ibáñez

Alarcón-Lladó

Cuscó

et al. 2007

Journal of Applied Physics

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We present a Raman-scattering study on strain-free dilute Ga͑As,N͒ epilayers grown by molecular beam epitaxy. The aim of our work is to discriminate the effect of alloying from the effect of biaxial strain on the frequency behavior of the optical phonon modes of Ga͑As,N͒. In the relaxed epilayers, we observe the following: ͑i͒ for the GaN-like LO mode, an upward frequency shift with increasing N which is larger than previously observed in strained samples; ͑ii͒ for the GaAs-like LO mode, a redshift with increasing N content which is lower than those reported in the literature on strained samples; and ͑iii͒ for the GaAs-like TO mode, we observe a very minor blueshift with increasing N fraction. We discuss the origin of the observed shifts, with particular attention to the reduction of the GaAs-like TO-LO splitting in Ga͑As,N͒. Our data and analysis suggest that such reduction cannot be explained only by a reduction of the total number of Ga-As oscillators due to the substitution of As by N. We discuss the effects of disorder and of ionic plasmon coupling between the GaAs and GaN sublattices of Ga͑As,N͒ on the behavior of the GaAs-like LO mode of the alloy. We conclude that the behavior of this mode is determined by long-range effects.

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Section: Gaas-like To-lo Splittingsupporting

confidence: 68%

Section: Gaas-like To-lo Splittingmentioning

confidence: 99%

Section: Gaas-like To-lo Splittingmentioning

confidence: 99%

Section: Gaas-like To-lo Splittingmentioning

confidence: 99%

Section: Gaas-like To-lo Splittingmentioning

confidence: 99%

See 3 more Smart Citations

Optical phonon behavior in strain-free dilute Ga(As,N) studied by Raman scattering

Ibáñez

Alarcón-Lladó

Cuscó

et al. 2007

Journal of Applied Physics

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Disorder Effects and Resonant Features in Raman Spectra of Electron-Irradiated GaP and CdS Crystals

Azhniuk

Gomonnai

Goyer

et al. 2001

phys. stat. sol. (b)

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Electron-irradiated (by 7-14 MeV electrons) GaP and CdS crystals and CdS-based solid solutions were studied by Raman scattering. Disorder-activated acoustic phonon bands are revealed in the GaP spectrum with increase of the irradiation dose. Broadening of the TO-phonon band in irradiated GaP samples is observed. The behaviour of the LO-and 2LO-phonon resonant Raman scattering versus irradiation dose is discussed, the resonant conditions being tuned by variation of exciting light energy and crystal composition.

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Microscopical Quantification of Ion‐Induced Nanodefects in Monolayer MoS₂ Based on Differential Reflectance

Qiu

Wang

et al. 2021

Adv Materials Inter

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microscope [17,18] (EM), inherent disadvantages of EM method have limited its application due to the expensive and timeconsuming characteristics, and the incapability of large-area test. Another kind of characterizing method is to analyze defects reversely from the measured changes of material properties. For example, the defect density in graphene is evaluated by the Raman intensity ratio of I D /I G , [19,20] and defects in WSe 2 are monitored by the photoluminescence (PL) intensity ratio of I Xb /I X0 . [21] However, the indirect characterizing method still requires an acquisition time of seconds per pixel. Thus, it is necessary to explore a new defect quantification method which is cheap, practical, and of high-speed imaging for large-area online inspection tasks. Here, we develop a practical defect quantification method based on differential reflectance spectroscopy (DRS) mapping. DRS is widely used in thin film characterization, [22][23][24][25][26] and it is well known for the ability to characterize large-area inhomogeneity of stacked thin films at sublayer precision. [27] For example, DRS was used for real-time monitoring of 2D semiconductor film growth. [22,24] As for high-speed imaging, the hyperspectral imaging [28,29] (HSI) technique could be combined as DRS measures the strong first-order optical signal. By taking a series of photos in response to different spectral ranges, HSI performs rapid spectral imaging beyond point-scanning methods. In this paper, a typical 2D semiconductor MoS 2 is selected as the model material due to easy calibration of its defect density by the defect activated Raman characteristic peak at ≈227 cm -1 . [30][31][32] Defects with different densities are induced into monolayer MoS 2 (ML-MoS 2 ) by focused ion beam (FIB) irradiation. The large-area defect mapping of ML-MoS 2 is performed by monochromatic photos after the DRS study. The feasibility of DRS mapping is demonstrated which is expected to achieve high-throughput online detect inspection for 2D materials. Results and Discussion Raman Characterization of ML-MoS 2 Defect SamplesAs a nondestructive vibrational spectroscopy technique, Raman spectroscopy can provide detailed information about chemical structure, phase, crystallinity, and molecular interactions. The layer-number identification of mechanically exfoliated MoS 2 samples was performed by Raman microscopyThe defect engineering is widely used in 2D heterostructure devices as nanodefects (like atomic vacancies) significantly alter the electronic, mechanical, and optical properties of 2D nanomaterials. Defect inspection on large-area samples at video rates is requisite for semiconductor manufacturing industry. Take molybdenum disulfide (MoS 2 ) as the study case, the differential reflectance spectroscopy (DRS) is first introduced into nanodefect quantification of 2D materials. Different densities of defects are induced by ion bombardment and the average interdefect distance L D is calibrated using Raman spectra analysis. The evolutions of several defect-induced DR...

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Phonon shifts in ion bombarded GaAs: Raman measurements

Cited by 71 publications

References 25 publications

Optical phonon behavior in strain-free dilute Ga(As,N) studied by Raman scattering

Optical phonon behavior in strain-free dilute Ga(As,N) studied by Raman scattering

Disorder Effects and Resonant Features in Raman Spectra of Electron-Irradiated GaP and CdS Crystals

Microscopical Quantification of Ion‐Induced Nanodefects in Monolayer MoS₂ Based on Differential Reflectance

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Phonon shifts in ion bombarded GaAs: Raman measurements

Cited by 71 publications

References 25 publications

Optical phonon behavior in strain-free dilute Ga(As,N) studied by Raman scattering

Optical phonon behavior in strain-free dilute Ga(As,N) studied by Raman scattering

Disorder Effects and Resonant Features in Raman Spectra of Electron-Irradiated GaP and CdS Crystals

Microscopical Quantification of Ion‐Induced Nanodefects in Monolayer MoS2 Based on Differential Reflectance

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Microscopical Quantification of Ion‐Induced Nanodefects in Monolayer MoS₂ Based on Differential Reflectance