Raman and photoluminescence studies of biaxial strain in GaN epitaxial layers grown on 6H–SiC

Davydov, V. Yu.; Averkiev, N. S.; Goncharuk, I. N.; Nelson, D. K.; Никитина, И.П.; Polkovnikov, Anatoli; Смирнов, А. Н.; Jacobson, M.A.; Semchinova, O.

doi:10.1063/1.366310

Cited by 361 publications

(168 citation statements)

References 20 publications

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“…5͒. The slope of this linear fit has the value kϭϪ8.7Ϯ0.6 eV, which is in good agreement with the data reported in the literature 8,19 (Ϫ8.4 eV and Ϫ9.4 eV, respectively͒. From this fit we can estimate the position of the D 0 X transition for relaxed GaN to 3.462 eV.…”

Section: Plsupporting

confidence: 78%

Structural and optical properties of Si-doped GaN

et al. 2000

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Structural and optical properties of Si-doped GaN thin films grown by metal-organic chemical vapor deposition have been studied by means of high resolution x-ray diffraction ͑XRD͒, atomic force microscopy, photoluminescence, photothermal deflection spectroscopy, and optical transmission measurements. The incorporation of silicon in the GaN films leads to pronounced tensile stress. The energy position of the neutral donor bound excitonic emission correlates with the measured stress. The stress induced near band gap luminescence shift is estimated to 19Ϯ2 meV/GPa. An increasing concentration of dopant impurities in the films leads to asymmetries of the XRD and photoluminescence spectra, which are probably related to a stress induced inhomogeneous distribution of dopants. Atomic force microscopy observations of surface modulation with increasing silicon doping support this latter statement. Transmission and photothermal deflection spectroscopy measurements are used to determine the band gap energy and Urbach energy of highly doped samples.

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Section: Plsupporting

confidence: 78%

Structural and optical properties of Si-doped GaN

et al. 2000

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“…where σ is the biaxial stress, Δω is the Raman shift, and k is the Raman stress coefficient of 6.2 cm −1 •GPa −1 for GaN [34]. Generally, a blue shift in an E2-high phonon peak indicates compressive To further clarify the stress behaviors among the four samples, Raman scattering spectroscopy was performed, and the results are shown in Figure 6.…”

Section: Resultsmentioning

confidence: 99%

“…where σ is the biaxial stress, ∆ω is the Raman shift, and k is the Raman stress coefficient of 6.2 cm −1 ·GPa −1 for GaN [34]. Generally, a blue shift in an E 2 -high phonon peak indicates compressive stress, while a red shift indicates tensile stress [35].…”

Section: Resultsmentioning

confidence: 99%

Optoelectronic Properties and Structural Characterization of GaN Thick Films on Different Substrates through Pulsed Laser Deposition

et al. 2017

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Approximately 4-µm-thick GaN epitaxial films were directly grown onto a GaN/sapphire template, sapphire, Si(111), and Si(100) substrates by high-temperature pulsed laser deposition (PLD). The influence of the substrate type on the crystalline quality, surface morphology, microstructure, and stress states was investigated by X-ray diffraction (XRD), photoluminescence (PL), atomic force microscopy (AFM), transmission electron microscopy (TEM), and Raman spectroscopy. Raman scattering spectral analysis showed a compressive film stress of −0.468 GPa for the GaN/sapphire template, whereas the GaN films on sapphire, Si(111), and Si(100) exhibited a tensile stress of 0.21, 0.177, and 0.081 GPa, respectively. Comparative analysis indicated the growth of very close to stress-free GaN on the Si(100) substrate due to the highly directional energetic precursor migration on the substrate's surface and the release of stress in the nucleation of GaN films during growth by the high-temperature (1000 • C) operation of PLD. Moreover, TEM images revealed that no significant GaN meltback (Ga-Si) etching process was found in the GaN/Si sample surface. These results indicate that PLD has great potential for developing stress-free GaN templates on different substrates and using them for further application in optoelectronic devices.

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“…20 In a good approximation, it can be assumed that Δk = −2a·ε xx − b·ε zz where a and b are the socalled phonon deformation potential constants. 29 In the present case this can be simplified to Δk ≈ −b·ε zz where lateral strain contributions ε xx can be neglected. Consequently, an experimental value from Raman measurements for ε zz can be directly calculated for a given value of the parameter b.…”

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confidence: 97%

Strain-Induced Band Gap Engineering in Selectively Grown GaN–(Al,Ga)N Core–Shell Nanowire Heterostructures

et al. 2016

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We demonstrate the selective area growth of GaN−(Al,Ga)N core−shell nanowire heterostructures directly on Si(111). Photoluminescence spectroscopy on as-grown nanowires reveals a strong blueshift of the GaN band gap from 3.40 to 3.64 eV at room temperature. Raman measurements relate this shift to compressive strain within the GaN core. On the nanoscale, cathodoluminescence spectroscopy and scanning transmission electron microscopy prove the homogeneity of strain-related luminescence along the nanowire axis and the absence of significant fluctuations within the shell, respectively. A comparison of the experimental findings with numerical simulations indicates the absence of a significant defect-related strain relaxation for all investigated structures, with a maximum compressive strain of −3.4% for a shell thickness of 50 nm. The accurate control of the nanowire dimensions, namely, core diameter, shell thickness, and nanowire period, via selective area growth allows a specific manipulation of the resulting strain within individual nanowires on the same sample. This, in turn, enables a spatially resolved adjustment of the GaN band gap with an energy range of 240 meV in a one-step growth process.

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Raman and photoluminescence studies of biaxial strain in GaN epitaxial layers grown on 6H–SiC

Cited by 361 publications

References 20 publications

Structural and optical properties of Si-doped GaN

Structural and optical properties of Si-doped GaN

Optoelectronic Properties and Structural Characterization of GaN Thick Films on Different Substrates through Pulsed Laser Deposition

Strain-Induced Band Gap Engineering in Selectively Grown GaN–(Al,Ga)N Core–Shell Nanowire Heterostructures

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