In rich In1−x
 
Ga
 x
 
N: Composition dependence of longitudinal optical phonon energy

Tiraş, E.; Güneş, Mustafa; Balkan, N.; Schaff, William J.

doi:10.1002/pssb.200945144

Cited by 13 publications

(14 citation statements)

References 40 publications

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“…At high temperatures polar optical phonon scattering is the dominant scattering mechanism in GaN [19]. The LO phonon scattering limited mobility (μ LO ) can be extracted from the measured Hall mobility by rewriting Matthiessen's rule [33] as…”

Section: Resultsmentioning

confidence: 99%

Determination of the LO phonon energy by using electronic and optical methods in AlGaN/GaN

et al. 2012

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Abstract:The longitudinal optical (LO) phonon energy in AlGaN/GaN heterostructures is determined from temperature-dependent Hall effect measurements and also from Infrared (IR) spectroscopy and Raman spectroscopy. The Hall effect measurements on AlGaN/GaN heterostructures grown by MOCVD have been carried out as a function of temperature in the range 1.8-275 K at a fixed magnetic field. The IR and Raman spectroscopy measurements have been carried out at room temperature. The experimental data for the temperature dependence of the Hall mobility were compared with the calculated electron mobility. In the calculations of electron mobility, polar optical phonon scattering, ionized impurity scattering, background impurity scattering, interface roughness, piezoelectric scattering, acoustic phonon scattering and dislocation scattering were taken into account at all temperatures. The result is that at low temperatures interface roughness scattering is the dominant scattering mechanism and at high temperatures polar optical phonon scattering is dominant. PACS

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Section: Resultsmentioning

confidence: 99%

Determination of the LO phonon energy by using electronic and optical methods in AlGaN/GaN

et al. 2012

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“…3 for a review on III-V alloys). Numerous studies have been devoted to study the vibrational properties of hexagonal InGaN thin films [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] and InGaN/GaN quantum wells. [22][23][24] Although it is well accepted that both the A 1 (LO) and the E 2h phonon modes of InGaN display a one-mode behavior, 15,16 there are still open questions regarding the behavior of the optical phonons in the InGaN alloy.…”

Section: Introductionmentioning

confidence: 99%

“…Such deviations are usually attributed to the strain of the samples. 12,20 However, many authors have shown that the A 1 (LO) frequency strongly depends on the excitation wavelength and/or on temperature, and different effects have been invoked to explain the observations: i) strain and/or compositional gradients over depth; 13,19 ii) compositional inhomogeneities giving rise to selective resonant excitation of domains with a particular In content; 5,7,15,17 iii) relaxation of the wave-vector selection rule. 18 Thus, it remains necessary to identify which mechanisms are actually playing a key role in the behavior of the A 1 (LO) mode of InGaN.…”

Section: Introductionmentioning

confidence: 99%

Raman scattering by the E2h and A1(LO) phonons of InxGa1−xN epilayers (0.25 < x < 0.75) grown by molecular beam epitaxy

Oliva

Ibáñez

Cuscó

et al. 2012

Journal of Applied Physics

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We use Raman scattering to investigate the composition behavior of the E 2h and A 1 (LO) phonons of In x Ga 1Àx N and to evaluate the role of lateral compositional fluctuations and in-depth strain/ composition gradients on the frequency of the A 1 (LO) bands. For this purpose, we have performed visible and ultraviolet Raman measurements on a set of high-quality epilayers grown by molecular beam epitaxy with In contents over a wide composition range (0.25 < x < 0.75). While the as-measured A 1 (LO) frequency values strongly deviate from the linear dispersion predicted by the modified random-element isodisplacement (MREI) model, we show that the strain-corrected A 1 (LO) frequencies are qualitatively in good agreement with the expected linear dependence. In contrast, we find that the strain-corrected E 2h frequencies exhibit a bowing in relation to the linear behavior predicted by the MREI model. Such bowing should be taken into account to evaluate the composition or the strain state of InGaN material from the E 2h peak frequencies. We show that in-depth strain/composition gradients and selective resonance excitation effects have a strong impact on the frequency of the A 1 (LO) mode, making very difficult the use of this mode to evaluate the strain state or the composition of InGaN material. V C 2012 American Institute of Physics.

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“…The thickness of Ga x In 1Àx N layer were estimated from growth parameters and verified by Rutherford backscattering spectrometry as 500 nm. 11 Since the critical thickness of Ga x In 1Àx N alloys (0 < x < 0.56) is less than 10 nm, 12,13 we may assume that Ga x In 1Àx N alloys are fully relaxed. The free carrier concentrations were obtained from Hall Effect measurements.…”

Section: Methodsmentioning

confidence: 99%

High carrier concentration induced effects on the bowing parameter and the temperature dependence of the band gap of GaxIn1−xN

Donmez

Güneş

Erol

et al. 2011

Journal of Applied Physics

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The influence of intrinsic carrier concentration on the compositional and temperature dependence of the bandgap of Ga x In 1Àx N is investigated in nominally undoped samples with Ga fractions of x ¼ 0.019, 0.062, 0.324, 0.52, and 0.56. Hall Effect results show that the free carrier density has a very weak temperature dependence and increases about a factor of 4, when the Ga composition increases from x ¼ 0.019 to 0.56. The photoluminescence (PL) peak energy has also weak temperature dependence shifting to higher energies and the PL line shape becomes increasingly asymmetrical and broadens with increasing Ga composition. The observed characteristics of the PL spectra are explained in terms of the transitions from free electron to localized tail states and the high electron density induced many-body effects. The bowing parameter of Ga x In 1Àx N is obtained from the raw PL data as 2.5 eV. However, when the high carrier density induced effects are taken into account, it increases by about 14% to 2.9 eV. Furthermore, the temperature dependence of the PL peak becomes more pronounced and follows the expected temperature dependence of the bandgap variation.

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In rich In_1−x Ga_x N: Composition dependence of longitudinal optical phonon energy

Cited by 13 publications

References 40 publications

Determination of the LO phonon energy by using electronic and optical methods in AlGaN/GaN

Determination of the LO phonon energy by using electronic and optical methods in AlGaN/GaN

Raman scattering by the E2h and A1(LO) phonons of InxGa1−xN epilayers (0.25 < x < 0.75) grown by molecular beam epitaxy

High carrier concentration induced effects on the bowing parameter and the temperature dependence of the band gap of GaxIn1−xN

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In rich In1−x Ga x N: Composition dependence of longitudinal optical phonon energy

Cited by 13 publications

References 40 publications

Determination of the LO phonon energy by using electronic and optical methods in AlGaN/GaN

Determination of the LO phonon energy by using electronic and optical methods in AlGaN/GaN

Raman scattering by the E2h and A1(LO) phonons of InxGa1−xN epilayers (0.25 &lt; x &lt; 0.75) grown by molecular beam epitaxy

High carrier concentration induced effects on the bowing parameter and the temperature dependence of the band gap of GaxIn1−xN

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In rich In_1−x Ga_x N: Composition dependence of longitudinal optical phonon energy

Raman scattering by the E2h and A1(LO) phonons of InxGa1−xN epilayers (0.25 < x < 0.75) grown by molecular beam epitaxy