Reduction of the energy gap pressure coefficient of GaN due to the constraining presence of the sapphire substrate

Perlin, P.; Mattos, Laila; Shapiro, Noad A.; Krüger, Joachim; Wong, William S.; Sands, Timothy D.; Cheung, N.W.; Weber, E. R.

doi:10.1063/1.369554

Cited by 90 publications

(54 citation statements)

References 19 publications

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“…For instance, studies of the composition dependence of the band gaps in In-rich In 1-x Ga x N and In 1-x Al x N alloys have led to new values of the bowing parameters that are much lower than those previously determined by assuming the band gap of InN to be 1.9 eV [6]. There have been only a few experimental studies on the pressure behavior of GaN [7][8][9], Ga-rich In 1-x Ga x N alloys [8,10] and AlN [11]. Although there is a relatively good consensus on the band gap pressure coefficients of GaN and AlN, much less is known about the pressure dependence of the energy gaps in In containing group III-nitride alloys.…”

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confidence: 99%

Hydrostatic pressure dependence of the fundamental bandgap of InN and In-rich group III nitride alloys

Haller

et al. 2003

Applied Physics Letters

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We report studies of the hydrostatic pressure dependence of the fundamental bandgap of InN, In-rich In 1-x Ga x N (0 < x < 0.5) and In 1-x Al x N (x = 0.25) alloys. The bandgap shift with pressure was measured by optical absorption experiments with samples mounted in diamond anvil cells. The pressure coefficient is found to be 3.0±0.1 meV/kbar for InN. A comparison between our results and previously reported theoretical calculations is presented and discussed. Together with previous experimental results, our data suggest that the pressure coefficients of group-III nitride alloys have only a weak dependence on the alloy composition. The photoluminescence signals appear to yield significantly smaller pressure coefficients than the bandgap from absorption measurements. This is due to emission associated with highly localized states. Based on these results, the absolute deformation potentials of the conduction and valence band edges are estimated.

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confidence: 99%

Hydrostatic pressure dependence of the fundamental bandgap of InN and In-rich group III nitride alloys

Haller

et al. 2003

Applied Physics Letters

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“…As a result the experimental data for GaN are scattered over a very large range. 10,11,[14][15][16][17] For AlN and InN no experimental data are available, except for the hydrostatic deformation potential of the band gap in InN. 18 Previous theoretical studies have also produced widely differing values, resulting in a large uncertainty range.…”

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confidence: 99%

Strain effects in group-III nitrides: Deformation potentials for AlN, GaN, and InN

Yan

Rinke

Scheffler

et al. 2009

Applied Physics Letters

163

120

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A systematic density functional theory (DFT) study of strain effects on the electronic band structure of the group-III nitrides (AlN, GaN and InN) is presented. To overcome the deficiencies of the local-density and generalized gradient approximations (LDA and GGA) the Heyd-Scuseria-Ernzerhof hybrid functional (HSE) is used. Cross-checks for GaN demonstrate good agreement between HSE and exact-exchange based G0W0 calculations. We observe a pronounced nonlinear dependence of band-energy differences on strain. For realistic strain conditions in the linear regime around the experimental equilibrium volume a consistent and complete set of deformation potentials is derived.PACS numbers: 71.20. Nr, 71.70.Fk, 85.60.Bt The group-III nitride compounds and their alloys have recently received considerable attention as a versatile materials class. AlN, GaN and InN all crystallize in the wurtzite structure, but have vastly different band gaps ranging from 6.0 eV for AlN down to 0.7 eV for InN. For light emitting diodes (LEDs) 1 and laser diodes (LDs) 2,3 the group-III-nitrides are currently the only commercially available materials class for the green to the deep ultraviolet part of the spectrum, and future applications as chemical sensors, 4 in quantum cryptography 5 or in photocatalysis 6 are being explored. Applications in solid state lighting, however, are currently limited by loss mechanisms 7,8 and a deeper understanding of the fundamental materials properties is required. One crucial factor is the effect of strain.Due to the large differences in lattice parameters and thermal expansion coefficients between the substrate and the nitride overlayers, and between nitride layers with different alloy compositions, strain is always present in group-III-nitride based devices. Strain influences the optical properties, 9-11 in particular the energy of optical transitions, and for nonpolar or semipolar devices the polarization of the emitted light. 12 The effects of strain are characterized by the change of a transition energy (energy difference) upon application of strain, and the linear coefficient is defined as deformation potential. Together with the Luttinger (band) parameters, the deformation potentials constitute essential input for device modeling. 13 The experimental determination of deformation potentials is quite difficult, and aggravated by the fact that not all strain components can be determined accurately or without further approximations and that the deformation potentials cannot be isolated from each other, because uniaxial and biaxial strain cannot be applied separately. As a result the experimental data for GaN are scattered over a very large range. 10,11,14-17 For AlN and InN no experimental data are available, except for the hydrostatic deformation potential of the band gap in InN. 18 Previous theoretical studies have also produced widely differing values, resulting in a large uncertainty range. [19][20][21] The error bars can, in part, be attributed to the band-gap problem of density functional theory (DF...

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“…[6] and experimental data of dE E /dp from Ref. [7]. (b) Measured values of dE E /dp of In x Ga 1-x N QWs with x = 15 -20% as a function of QW width.…”

Section: Experimental Results: Influence Of Piefs and In Content On Dmentioning

confidence: 99%

“…[6] and the value of dE E /dp for GaN as reported in Ref. [7]. We can assume that the luminescence is associated with the band gap, i.e.…”

Section: Experimental Results: Influence Of Piefs and In Content On Dmentioning

confidence: 99%

Investigation of polarization‐induced electric field screening in InGaN light emitting diodes by means of hydrostatic pressure

Franssen

Suski

Perlin

et al. 2006

Physica Status Solidi (b)

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We show that the hydrostatic pressure coefficient dE E /dp of luminescence in In x Ga 1-x N epilayers is in the range 20 -38 meV/GPa for the entire alloy (0 ≥ x ≥ 1) and corresponds roughly to the bandgap increase with applied pressure. It is argued that lowering of dE E /dp in quantum structures of InGaN with respect to this range can be attributed to polarization-induced electric fields (PIEFs). Possible contribution to dE E /dp originating from In-segregation effects is of secondary importance. This information is used to investigate PIEF screening by free carriers in InGaN-based light emitting diodes (LEDs). We observe that Si doping at a level of 10 19 cm -2 of the barriers in the active region of such LEDs leads to a significant increase of dE E /dp as compared to LEDs with undoped barriers. This is evidence for efficient screening of PIEFs in the Si-doped devices.

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Reduction of the energy gap pressure coefficient of GaN due to the constraining presence of the sapphire substrate

Cited by 90 publications

References 19 publications

Hydrostatic pressure dependence of the fundamental bandgap of InN and In-rich group III nitride alloys

Hydrostatic pressure dependence of the fundamental bandgap of InN and In-rich group III nitride alloys

Strain effects in group-III nitrides: Deformation potentials for AlN, GaN, and InN

Investigation of polarization‐induced electric field screening in InGaN light emitting diodes by means of hydrostatic pressure

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