Far-infrared transmission in GaN, AlN, and AlGaN thin films grown by molecular beam epitaxy

Ibáñez, J.; Hernández, S.; Alarcón-Lladó, Esther; Cuscó, R.; Artús, L.; Novikov, S.V.; Foxon, C.T.; Calleja, E.

doi:10.1063/1.2968242

Cited by 43 publications

(28 citation statements)

References 26 publications

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“…This feature could be used to tune the transparency of GaN in the 1-7 µm spectral range. In general, the free carrier absorption is a well-known phenomenon in semiconductors which has been also observed for n-type GaN [13][14][15][20][21][22]. In order to compare our experimental results Figure 3a shows transmission spectra measured at room temperature for GaN crystals doped by oxygen with various concentrations of free electrons.…”

Section: Resultsmentioning

confidence: 99%

“…In general, the free carrier absorption is a well-known phenomenon in semiconductors which has been also observed for n-type GaN [13][14][15][20][21][22]. In order to compare our experimental results In general, the free carrier absorption is a well-known phenomenon in semiconductors which has been also observed for n-type GaN [13][14][15][20][21][22]. In order to compare our experimental results with a quantitative analysis, the plasma frequency (ω P ) has been calculated for various carrier concentrations according to Equation (2)…”

Section: Resultsmentioning

confidence: 99%

“…Ammonothermal bulk GaN crystals can be grown with an intended conductivity level by controlling the unintentional oxygen content during the growth process, leading to an electron concentration up to~10 20 cm −3 (n-type) and an intentional Mg concentration up to~10 19 cm −3 (p-type) [7]. The ammonothermal method can also obtain semi-insulating (SI) GaN crystals which are crucial for power electronics [8] via appropriate compensation of oxygen donors by Mg acceptors.…”

Section: Introductionmentioning

confidence: 99%

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Transparency of Semi-Insulating, n-Type, and p-Type Ammonothermal GaN Substrates in the Near-Infrared, Mid-Infrared, and THz Spectral Range

et al. 2017

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GaN substrates grown by the ammonothermal method are analyzed by Fast Fourier Transformation Spectroscopy in order to study the impact of doping (both n-and p-type) on their transparency in the near-infrared, mid-infrared, and terahertz spectral range. It is shown that the introduction of dopants causes a decrease in transparency of GaN substrates in a broad spectral range which is attributed to absorption on free carriers (n-type samples) or dopant ionization (p-type samples). In the mid-infrared the transparency cut-off, which for a semi-insulating GaN is at~7 µm due to an absorption on a second harmonic of optical phonons, shifts towards shorter wavelengths due to an absorption on free carriers up to~1 µm at n~10 20 cm −3 doping level. Moreover, a semi-insulating GaN crystal shows good transparency in the 1-10 THz range, while for n-and p-type crystal, the transparency in this spectral region is significantly quenched below 1%. In addition, it is shown that in the visible spectral region n-type GaN substrates with a carrier concentration below 10 18 cm −3 are highly transparent with the absorption coefficient below 3 cm −1 at 450 nm, a satisfactory condition for light emitting diodes and laser diodes operating in this spectral range.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Transparency of Semi-Insulating, n-Type, and p-Type Ammonothermal GaN Substrates in the Near-Infrared, Mid-Infrared, and THz Spectral Range

et al. 2017

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“…The long-wave low absorption can be related to disorder of tens-nanometer size grains in AlN layers deposited onto (111) Si substrates, although the long-wave shift with AlN thickness increase can be observed in thin wurtzite AlN layers on Si substrates. 28 The long-wave transparency shift observed in thick AlN layers is obviously caused by random orientation of c-axes in grains having the wurtzite structure. In this case, A1(TO), A1(LO), E1(TO), or E1(LO) modes can be seen.…”

Section: Optical and Morphological Propertiesmentioning

confidence: 99%

Infrared blocking, microwave and terahertz low-loss transmission AlN films grown on flexible polymeric substrates

Rudenko

Tsybrii

Сизов

et al. 2017

Journal of Applied Physics

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Aluminum nitride (AlN) film coatings on flexible substrates (polymeric Teflon, Mylar) have been obtained using a hybrid helicon-arc ion-plasma deposition technique with high adhesion of coatings. Studies of optical, morphological, and structural properties of AlN films have been carried out. It was found that AlN coatings on Teflon and Mylar thin-film substrates substantially suppress transmission of infrared (IR) radiation within the spectral range λ ∼ 5–20 μm at certain technological parameters and thickness of AlN. Transmission in THz regions by using quasioptics attains T ≈ 79%–95%, and losses measured in the channels within the microwave region 2 to 36 GHz are <0.06 dB. The obtained composite structures (AlN coatings on Teflon and Mylar thin-film substrates), due to a high thermal conductivity of AlN, could be used as efficient blocking structures in the infrared spectral range (“infrared stealth”) withdrawing the heat from filters warmed by IR radiation. At the same time, they can be used as the transparent ones in the microwave and THz regions, which can be important for low-temperature detector components of navigation, positioning, and telecommunication systems due to reducing the background noise.

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“…The 3.4 μm band results from a resonance formed by the lossy AlN dielectric (ε r extracted to be 3.6 − j 0.09) and the bottom metal electrode as confirmed by finite integration technique (FIT) simulation in the software computer simulation technology. The 11.3 μm and 15.5 μm peaks correspond to two intrinsic vibrational bands of the AlN 35 (which are not modeled in the FIT simulation). As shown in Figure 4, 4100 × improvement in absorptance, η, at 3.4 μm, and~10 × improvement at 5 μm were recorded for the G-AlN devices compared with the reference devices employing a highly reflective top gold electrode.…”

Section: Ir Detectionmentioning

confidence: 99%

Graphene–aluminum nitride NEMS resonant infrared detector

et al. 2016

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The use of micro-/nanoelectromechanical resonators for the room temperature detection of electromagnetic radiation at infrared frequencies has recently been investigated, showing thermal detection capabilities that could potentially outperform conventional microbolometers. The scaling of the device thickness in the nanometer range and the achievement of high infrared absorption in such a subwavelength thickness, without sacrificing the electromechanical performance, are the two key challenges for the implementation of fast, high-resolution micro-/nanoelectromechanical resonant infrared detectors. In this paper, we show that by using a virtually massless, high-electrical-conductivity, and transparent graphene electrode, floating at the van der Waals separation of a few angstroms from a piezoelectric aluminum nitride nanoplate, it is possible to implement ultrathin (460 nm) piezoelectric nanomechanical resonant structures with improved electromechanical performance (450% improved frequency × quality factor) and infrared detection capabilities (4100 × improved infrared absorptance) compared with metal-electrode counterparts, despite their reduced volumes. The intrinsic infrared absorption capabilities of a submicron thin graphene-aluminum nitride plate backed with a metal electrode are investigated for the first time and exploited for the first experimental demonstration of a piezoelectric nanoelectromechanical resonant thermal detector with enhanced infrared absorptance in a reduced volume. Moreover, the combination of electromagnetic and piezoelectric resonances provided by the same graphene-aluminum nitride-metal stack allows the proposed device to selectively detect short-wavelength infrared radiation (by tailoring the thickness of aluminum nitride) with unprecedented electromechanical performance and thermal capabilities. These attributes potentially lead to the development of uncooled infrared detectors suitable for the implementation of high performance, miniaturized and power-efficient multispectral infrared imaging systems.

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Far-infrared transmission in GaN, AlN, and AlGaN thin films grown by molecular beam epitaxy

Cited by 43 publications

References 26 publications

Transparency of Semi-Insulating, n-Type, and p-Type Ammonothermal GaN Substrates in the Near-Infrared, Mid-Infrared, and THz Spectral Range

Transparency of Semi-Insulating, n-Type, and p-Type Ammonothermal GaN Substrates in the Near-Infrared, Mid-Infrared, and THz Spectral Range

Infrared blocking, microwave and terahertz low-loss transmission AlN films grown on flexible polymeric substrates

Graphene–aluminum nitride NEMS resonant infrared detector

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