Dielectric function and optical properties of quaternary AlInGaN alloys

Sakalauskas, E.; Reuters, B.; Khoshroo, L. Rahimzadeh; Kalisch, H.; Heuken, M.; Vescan, A.; Röppischer, Marcus; Cobet, Christoph; Gobsch, G.; Goldhahn, R.

doi:10.1063/1.3603015

Cited by 34 publications

(24 citation statements)

References 53 publications

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“…We use k Á p formalism [11] and employ the same parameters as provided in Ref. [6]. The in-plane strain is evaluated from the XRD measurements by using the expression e xx ¼ ða À a ) for the SB samples should be noticed.…”

Section: Resultsmentioning

confidence: 99%

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Dielectric function and bowing parameters of InGaN alloys

Sakalauskas

Tuna

Kraus

et al. 2012

Physica Status Solidi (b)

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Ga-rich (0001)-oriented In x Ga 1Àx N alloys grown by molecular beam epitaxy or metal-organic vapour phase epitaxy on GaN/ sapphire templates were investigated by spectroscopic ellipsometry at room temperature. The analysis of the extracted dielectric function yielded the characteristic transition energies, i.e., for the band gaps and the high-energy critical points (van Hove singularities). Accounting for strain by using the k Á p formalism, a band-gap bowing parameter of 1.65 AE 0.07 eV for strain-free material was deduced. It is consistent with the ab initio calculated band-gap-dependence for uniform (not clustered) InGaN alloys. The bowing parameters for the highenergy inter-band transitions were found to be close to $1 eV.

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Section: Resultsmentioning

confidence: 99%

“…The band-gap values for Ga-rich InGaN samples were obtained by fitting the experimental DF with the parametric oscillator model presented in Refs. [5,6].…”

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confidence: 98%

Dielectric function and bowing parameters of InGaN alloys

Sakalauskas

Tuna

Kraus

et al. 2012

Physica Status Solidi (b)

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“…1, is plotted as a function of the nominal lattice constant a, calculated by Vegard's law. Here, the bowing parameters are updated by the latest results from the literature: The bowing parameters used here are 0.9 eV for AlGaN, 17 1.65 eV for InGaN, 17 and a quite high and constant value of 5.2 eV for AlInN. 11,18 The bowing parameter for AlInN is still vague and might also be In dependent, especially for the In-rich region.…”

Section: Resultsmentioning

confidence: 99%

“…11,18 The bowing parameter for AlInN is still vague and might also be In dependent, especially for the In-rich region. 17 The contour lines in the quaternary area illustrate the total polarization of quaternary barriers for the corresponding barrier composition, being pseudomorphically grown on a GaN buffer. The thicker red line indicates polarization matching to GaN.…”

Section: Resultsmentioning

confidence: 99%

Polarization-Engineered Enhancement-Mode High-Electron-Mobility Transistors Using Quaternary AlInGaN Barrier Layers

Reuters

Wille

Ketteniss

et al. 2013

Journal of Elec Materi

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Group III nitride heterostructures with low polarization difference recently moved into the focus of research for realization of enhancement-mode (e-mode) transistors. Quaternary AlInGaN layers as barriers in GaN-based high-electron-mobility transistors (HEMTs) offer the possibility to perform polarization engineering, which allows control of the threshold voltage over a wide range from negative to positive values by changing the composition and strain state of the barrier. Tensile-strained AlInGaN layers with high Al contents generate high two-dimensional electron gas (2DEG) densities, due to the large spontaneous polarization and the contributing piezoelectric polarization. To lower the 2DEG density for e-mode HEMT operation, the polarization difference between the barrier and the GaN buffer has to be reduced. Here, two different concepts are discussed. The first is to generate compressive strain with layers having high In contents in order to induce a positive piezoelectric polarization compensating the large negative spontaneous polarization. Another novel approach is a lattice-matched Ga-rich AlInGaN/GaN heterostructure with low spontaneous polarization and improved crystal quality as strain-related effects are eliminated. Both concepts for e-mode HEMTs are presented and compared in terms of electrical performance and structural properties.

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“…It has been reported that growth of high crystalline quality AlInGaN layers is difficult [12], though such issues do not appear to be fundamental. Recently, Sakalauskas et al have grown a wide range of AlInGaN materials on c-place sapphire substrates with GaN templates [13] and studied their optical properties. They confirmed pseudomorphic growth of AlInGaN films by high-resolution x-ray diffraction measurements.…”

Section: Polarization Charge Matched Duv Ld Designmentioning

confidence: 99%

Advanced Middle-UV Coherent Optical Sources

Dupuis¹,

Lochner²,

Kao³

et al. 2013

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The overall goals of this program are to develop III-N deep-UV injection lasers operating at <250nm at 300K with CW output power greater than 5mW. The Georgia Tech program is divided into four primary tasks: (1) III-N Materials Growth and Evaluation; (2) Detailed III-N Materials Characterization; (3) III-N UV laser design and simulation; and (4) III-N UV laser processing, testing, and characterization. The recent efforts by the Georgia Tech/ASU team are summarized below. This report will focus on the recent work in the past six months of the program. Summary of Overall Program Major Accomplishments:1. We have developed MOCVD growth technologies for III-N deep-UV lasers on two different growth systems: the "standard" Thomas-Swan 6x2 Close-Coupled Showerhead MOCVD reactor using AlGaN-AlN growth conditions at ~1150C, and one new high-temperature AIXTRON 3x2 Close-Coupled Showerhead MOCVD system operating at up to ~1300C, (which was purchased partially with funds from this program), to allow us to explore "higher temperature" growth regimes. 2. We have exploited advanced high-resolution materials growth technologies, e.g., high-angle annular dark-field (HAADF) imaging, Rutherford Back Scattering, high-resolution TEM, and variable-temperature cathodoluminescence, to characterize the III-N wide-bandgap materials. 3. We have developed the most complete and advanced III-N device simulation tool and have utilized it to optimize the optical and electrical performance of deep-UV laser diodes at ~250nm. 4. We have developed and exercised the required III-N UV laser device processing, wafer thinning, facet cleaving, facet coating, and optical characterization techniques and exploited these processes to demonstrate optically pumped pulsed UV lasers at <250nm with thresholds as low as ~297 kW/cm 2 for lasers at =245.3 nm without facet coatings. 5. Additional studies of optically pumped lasers with one facet coated has shown 300K lasing at Report Documentation PageForm Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. REPORT DATE NOV 20132. REPORT TYPE We have developed MOCVD growth technologies for III-N deep-UV lasers on two different growth systems: the ?standard? Thomas-Swan 6x2 Close-Coupled Showerhead MOCVD reactor using AlGaN-AlN growth conditions at ~1150C, ...

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Dielectric function and optical properties of quaternary AlInGaN alloys

Cited by 34 publications

References 53 publications

Dielectric function and bowing parameters of InGaN alloys

Dielectric function and bowing parameters of InGaN alloys

Polarization-Engineered Enhancement-Mode High-Electron-Mobility Transistors Using Quaternary AlInGaN Barrier Layers

Advanced Middle-UV Coherent Optical Sources

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