Intersubband absorption of cubic GaN/Al(Ga)N quantum wells in the near-infrared to terahertz spectral range

Machhadani, H.; Tchernycheva, Maria; Sakr, S.; Rigutti, Lorenzo; Colombelli, R.; Warde, E.; Mietze, C.; As, D. J.; Julien, F. H.

doi:10.1103/physrevb.83.075313

Cited by 52 publications

(27 citation statements)

References 31 publications

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“…Non-polar nitride structures may be achieved using either the cubic phase or the m-plane orientation of the wurzite phase. Near-infrared intersubband absorption in the cubic AlGaN/GaN has been observed, 15 and m-plane oriented a) omalis@purdue.edu quantum well infrared photodetectors operating in the mid-infrared have recently been demonstrated. 16 However, THz intersubband transitions in non-polar nitrides have not yet been reported.…”

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confidence: 99%

Terahertz intersubband absorption in non-polar m-plane AlGaN/GaN quantum wells

Edmunds

Shao

Shirazi-HD

et al. 2014

Applied Physics Letters

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We demonstrate THz intersubband absorption (15.6-26.1 meV) in m-plane AlGaN/GaN quantum wells. We find a trend of decreasing peak energy with increasing quantum well width, in agreement with theoretical expectations. However, a blue-shift of the transition energy of up to 14 meV was observed relative to the calculated values. This blue-shift is shown to decrease with decreasing charge density and is therefore attributed to many-body effects. Furthermore, a ∼40% reduction in the linewidth (from roughly 8 to 5 meV) was obtained by reducing the total sheet density and inserting undoped AlGaN layers that separate the wavefunctions from the ionized impurities in the barriers.PACS numbers: 78.67. De, 78.66.Fd The terahertz (THz) spectral region has attracted attention due to potential applications in medical diagnostics, security screening and quality control. GaAs/AlGaAs quantum cascade lasers (QCLs) have already demonstrated potential as THz sources in the 1.2-5 THz range. 1-5 However, the operating range of GaAs QCLs is limited by the longitudinal optical (LO) phonon emission at 36 meV (8.7 THz). Fortunately, GaN-based QCLs have the potential to operate in this range due to the larger LO-phonon energy (90 meV).To date, most studies of intersubband transitions in the III-nitrides have utilized the polar c-plane orientation. 6-10 Spontaneous emission from c-plane AlGaN/GaN QCLs in the THz region has been reported, although full laser operation has remained elusive. 11 The built-in polarization fields in c-plane heterostructures place a lower limit on the transition energy, and the inherent asymmetry in the conduction band profile reduces the dipole moment at the larger well widths required for operation in the THz region. These limitations have been partially mitigated by the implementation of more complex step-well designs. 9,12 However, the transition energies of these step-wells are highly sensitive to structural parameters. 13,14 Moreover, the additional layers significantly increase the complexity of design and growth of practical devices. The challenges of the built-in polarization fields can be circumvented by utilizing non-polar nitride heterostructures. Non-polar nitride structures may be achieved using either the cubic phase or the m-plane orientation of the wurzite phase. Near-infrared intersubband absorption in the cubic AlGaN/GaN has been observed, 15 and m-plane oriented We have already demonstrated molecular beam epitaxy (MBE) growth of high-quality m-plane AlGaN/GaN superlattices. 17,18 In this study, the samples consist of 26 quantum wells (QWs) grown on free-standing m-plane

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confidence: 99%

Terahertz intersubband absorption in non-polar m-plane AlGaN/GaN quantum wells

Edmunds

Shao

Shirazi-HD

et al. 2014

Applied Physics Letters

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“…Furthermore, the presence of stacking faults, as an additional perturbation of the bands, contributes to the absorption line broadening. We note that Gaussian lineshapes of the ISB absorption has also been observed in cubic GaN/Al(Ga)N QWs 16 and can be explained in the same manner.…”

Section: Nature Of Isb Broadeningmentioning

confidence: 60%

“…For optoelectronic applications, it is, therefore, desirable to reduce the internal electric field. This can be achieved by using III-nitride materials synthesized in the cubic phase [13][14][15][16] or by changing the growth direction to set the polarization vector at 90 . 17 The later strategy has been implemented using nonpolar growth planes, namely, the m-plane f10 10g 18 or the a-plane f11 20g.…”

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confidence: 99%

Systematic study of near-infrared intersubband absorption of polar and semipolar GaN/AlN quantum wells

Machhadani

Beeler

Sakr

et al. 2013

Journal of Applied Physics

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We report on the observation of intersubband absorption in GaN/AlN quantum well superlattices grown on ð11 22Þ-oriented GaN. The absorption is tuned in the 1:5-4:5 lm wavelength range by adjusting the well thickness. The semipolar samples are compared with polar samples with identical well thickness grown during the same run. The intersubband absorption of semipolar samples shows a significant red shift with respect to the polar ones due to the reduction of the internal electric field in the quantum wells. The experimental results are compared with simulations and confirm the reduction of the polarization discontinuity along the growth axis in the semipolar case. The absorption spectral shape depends on the sample growth direction: for polar quantum wells the intersubband spectrum is a sum of Lorentzian resonances, whereas a Gaussian shape is observed in the semipolar case. This dissimilarity is explained by different carrier localization in these two cases. V C 2013 AIP Publishing LLC [http://dx

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“…Over the past few years, cubic Gan/AlGaN QW based photodetectors have been extensively investigated for detection of mid-IR and THz radiation [5,[12][13][14]. In this work we considered the design of optimal QW profiles in external electric field for the possible applications in tunable mid-IR photodetectors.…”

Section: Introductionmentioning

confidence: 99%

“…Besides their application in devices operating on the basis of interband transitions (laser and light emitting diodes in blue-green and ultraviolet spectral range [1][2][3]), electronic and optical properties of GaN and related materials make them particularly suitable for intersubband (ISB) based devices. Due to large values of the conduction band discontinuity and very short ISB absorption recovery times measured in femtoseconds, GaN/Al(Ga)N planar nanostructures are becoming the foremost system for ISB devices operating at telecommunication wavelengths, such as fast multiple quantum well (QW) photodetectors or modulators [4][5][6][7][8]. On the other hand, by changing the QW thickness and Al molar fraction in AlGaN alloy it is possible to tune the ISB absorption peak wavelength to mid-infrared (mid-IR) or terahertz (THz) spectral range, as well [5,[9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Cubic GaN/AlGaN based quantum wells optimized for applications to tunable mid-infrared photodetectors

et al. 2014

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Article:Radosavljevic, A, Radovanovic, J, Milanovic, V et al.(1 more author) (2015) Cubic GaN/AlGaN based quantum wells optimized for applications to tunable mid-infrared photodetectors. Optical and Quantum Electronics, 47 (4). [865][866][867][868][869][870][871][872] https://doi.org/10.1007/s11082-014-0016-y eprints@whiterose.ac.uk https://eprints.whiterose.ac.uk/ Reuse Unless indicated otherwise, fulltext items are protected by copyright with all rights reserved. The copyright exception in section 29 of the Copyright, Designs and Patents Act 1988 allows the making of a single copy solely for the purpose of non-commercial research or private study within the limits of fair dealing. The publisher or other rights-holder may allow further reproduction and re-use of this version -refer to the White Rose Research Online record for this item. Where records identify the publisher as the copyright holder, users can verify any specific terms of use on the publisher's website. TakedownIf you consider content in White Rose Research Online to be in breach of UK law, please notify us by emailing eprints@whiterose.ac.uk including the URL of the record and the reason for the withdrawal request. Abstract We propose a method which delivers optimal cubic GaN/AlGaN quantum well (QW) profiles such that both the Stark effect and peak intersubband absorption from the ground to the first excited electronic state, in a prescribed range of bias electric fields, are maximized. Our method relies on the Genetic Algorithm which finds globally optimal structures with a predefined number of embedded layers. We investigate simple rectangular quantum wells with embedded step layers for applications in tunable mid-infrared photodetectors. The effects of band nonparabolicity are taken into account to refine our model. Cubic GaN/AlGaN based quantum wells optimized for applications to tunable mid-infrared photodetectors

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Intersubband absorption of cubic GaN/Al(Ga)N quantum wells in the near-infrared to terahertz spectral range

Cited by 52 publications

References 31 publications

Terahertz intersubband absorption in non-polar m-plane AlGaN/GaN quantum wells

Terahertz intersubband absorption in non-polar m-plane AlGaN/GaN quantum wells

Systematic study of near-infrared intersubband absorption of polar and semipolar GaN/AlN quantum wells

Cubic GaN/AlGaN based quantum wells optimized for applications to tunable mid-infrared photodetectors

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