Optical studies of the phonons and electrons in gallium nitride

Manchon, Delphine; Barker, A. S.; Dean, P.D.G.; Zetterstrom, R. B.

doi:10.1016/0038-1098(70)90365-0

Cited by 182 publications

(61 citation statements)

References 8 publications

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“…The best fit was obtained for a permittivity of ε r = 4.9 ± 0.15, which can be considered as the effective dielectric constant of the GaN layer and AlGaN buffer-layer. The literature value for GaN and AlN in the high frequency limit is ranging from 5.35-5.8 and 4.16-4.84, respectively, depending on the E-field polarization and temperature [28][29][30][31][32]. This is consistent with our experimentally measured value of the GaN/AlGaN stack at 1.3 THz.…”

Section: Dielectric Constant Of the Gan/algan Membranesupporting

confidence: 91%

“…However, the balanced configuration is more complex than its single-ended counterpart and comprises of a RF hybrid, which combines the RF and LO single, two HEB mixers, which ideally exhibit identical electrical properties, and an in-phase IF combiner [30]. One pair of HEBs with 0.2 × 1.6 µm bridge dimensions are used for the characterization at 1.3 THz local oscillator (LO) frequency and their current-voltage characteristics (IVC) are depicted in figure 9.…”

Section: Balanced Waveguide Heterodyne Receiver At 13 Thzmentioning

confidence: 99%

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Suspended GaN beams and membranes on Si as a platform for waveguide-based THz applications

Krause

Desmaris

Pavolotsky

et al. 2018

J. Micromech. Microeng.

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Epitaxial growth of ultra-thin NbN films on AlxGa1-xN buffer-layers S Krause, D Meledin, V Desmaris et al. IntroductionThe exploration of the THz frequency range is constantly gaining speed and numerous applications have emerged within research, security, astronomy, biomedicine and metrology in recent years [1][2][3]. The main reason for this relatively late development can be attributed to several technological challenges that had to be overcome. As the dimensions of microwave components usually scale with the wavelength, their size presents a serious issue when the device operation frequency is approaching the THz range. This manifests itself in certain performance limitations due to parasitic capacitances, thermal issues, the excitation of unwanted electromagnetic (EM) modes or excessive RF losses in conductors as the skin depth may approach the roughness of the metal surface. Waveguides for guiding THz EM waves offer wideband operation and full confinement of the fields, yet they are also miniaturized and demand high surface quality and accuracy on the waveguide dimensions and alignment. Several different micro fabrication techniques [4] were developed for this purpose and are based on copper electroforming over a thick sacrificial photo resist mold [5,6] or deep Si etching processes [7]. In waveguidebased THz components, the actual substrate becomes more of a delicate membrane-like structure, which reduces the electrical loading of the waveguide and excludes substrate modes. However, it is difficult to manipulate and to place such beams suspended inside the waveguide with high alignment precision. Typically beam leads [8] made of thick electro-plated gold are used for the electrical contacting, however, once the device is mounted it can neither be modified nor removed in a non-destructive matter. One possible approach to overcome the aforementioned issues is based on a Π-shaped Si support frame holder [9], which keeps a thin Si membrane hosting the active device suspended. This concept has been successfully AbstractWe demonstrate the suitability of employing suspended GaN beams on a Π-shaped Si frame for waveguide-based cryogenic THz components and systems. This concept addresses major challenges and provides eased device handling, cryogenic operation, micron-alignment possibilities, high integratability and allows the electrical contacting by using bonding wires. In particular, a balanced hot electron bolometer (HEB) mixer was implemented for frequencies at 1.3 THz with state-of-the-art IF performance, which combines micro-machined all-metal waveguide components in conjunction with a suspended GaN beam. In addition, in order to accomplish a proper design of active or passive components, the accurate knowledge of the effective dielectric constant at THz frequencies is crucial when such membranes are employed. Thus, a direct measurement method based on a resonance structure and an S-parameter measurement between 1 THz and 1.5 THz is also presented.Keywords: THz components, GaN on Si, HEB, waveguide (Some f...

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Section: Dielectric Constant Of the Gan/algan Membranesupporting

confidence: 91%

Section: Balanced Waveguide Heterodyne Receiver At 13 Thzmentioning

confidence: 99%

Suspended GaN beams and membranes on Si as a platform for waveguide-based THz applications

Krause

Desmaris

Pavolotsky

et al. 2018

J. Micromech. Microeng.

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“…It shows the two Raman active optical phonon modes that, in theory, can be measured in this wavenumber range for hexagonal GaN in backscattering geometry if the GaN is c-axis oriented, i.e., A 1 (LO) and E 2 (high). 42 The E 2 (low) can, in principle, also be observed in hexagonal GaN, but it has a phonon frequency of 144 cm À1 and, therefore, is not visible in the displayed spectra. The A 1 (LO) phonon mode is here denoted as GaN (quasi-LO) because of its potential mixing with E 1 (LO) to produce a carrier concentration dependent coupled longitudinal optical mode.…”

Section: Influence On Structural Propertiesmentioning

confidence: 98%

Realising epitaxial growth of GaN on (001) diamond

Dreumel

Tinnemans

Heuvel

et al. 2011

Journal of Applied Physics

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By an extensive investigation of the principal growth parameters on the deposition process, we realized the epitaxial growth of crystalline wurtzite GaN thin films on single crystal (001) diamond substrates by metal organic chemical vapor deposition. From the influence of pressure, V/III ratio, and temperature, it was deduced that the growth process is determined by the mass-transport of gallium precursor material toward the substrate. The highest temperature yielded an improved epitaxial relationship between grown layer and substrate. X ray diffraction (XRD) pole figure analysis established the presence of two domains of epitaxial layers, namely (0001) h10 10i GaN k (001) [110] diamond and (0001) h10 10i GaN k (001) ½1 10 diamond, which are 90 rotated with respect to each other. The presence of these domains is explained by the occurrence of areas of (2 Â 1) and (1 Â 2) surface reconstruction of the diamond substrate. When applying highly misoriented diamond substrates toward the [110] diamond direction, one of the growth domains is suppressed and highly epitaxial GaN on (001) diamond is realized.

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“…The determination of the plasma frequency enabled the authors to evaluate the ratio of the free carrier concentration and the effective mass. Reflectivity studies were reported for samples with free carrier concentration in the 2 x 10 17 -1 x 1020 cm-3 range by Barker et al [2] and in the 10 19 cm-3 range by Manchon et al [4]. The correlation of the reflectivity spectrum with the results of Hall measurements allowed Barker et al to determine the value of the optical effective mass.…”

Section: Introductionmentioning

confidence: 96%

Reflectivity Studies of Lattice Vibrations and Free Electrons in MBE Grown GaN Epitaxial Layers

Iller¹,

Jantsch²,

Marks³

et al. 1998

Acta Phys. Pol. A

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We have observed a sharp structure with a peak at the frequency of the Ε1-ΤO phonon in the reflectivity of GaN epitaxial layers grown by molecular beam epitaxy on Si substrates. The simulations of the reflection performed show that the observed shape can be explained by assuming both collective lattice vibrations and free carriers contributions to the dielectric function. We assumed the Lorentz oscillator to describe the contribution of the collective lattice vibrations and the Drude-Lorentz model for that of free carriers. Fitting the calculated reflectivity to the spectrum obtained experimentally allowed us to evaluate lattice and free carrier parameters.

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Optical studies of the phonons and electrons in gallium nitride

Cited by 182 publications

References 8 publications

Suspended GaN beams and membranes on Si as a platform for waveguide-based THz applications

Suspended GaN beams and membranes on Si as a platform for waveguide-based THz applications

Realising epitaxial growth of GaN on (001) diamond

Reflectivity Studies of Lattice Vibrations and Free Electrons in MBE Grown GaN Epitaxial Layers

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