Optical properties of AlN determined by vacuum ultraviolet spectroscopy and spectroscopic ellipsometry data

Jones, David J.; French, Roger H.; Müllejans, Harald; Loughin, S.; Dorneich, A.; Carcia, P. F.

doi:10.1557/jmr.1999.0587

Cited by 64 publications

(38 citation statements)

References 43 publications

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“…To quantitatively determine the electronic structure of PS we have used Kramers-Kronig analysis [50,51] to determine the complex optical properties of PS over the complete energy range, encompassing the valence electronic structure. These results are essential information to calculate the full spectral Hamaker constants for vdW-Ld dispersion interactions for configurations including PS.…”

Section: Present Workmentioning

confidence: 99%

Optical Properties and van der Waals - London Dispersion Interactions of Polystyrene Determined by Vacuum Ultraviolet Spectroscopy and Spectroscopic Ellipsometry

et al. 2007

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The interband optical properties of polystyrene in the vacuum ultraviolet (VUV) region have been investigated using combined spectroscopic ellipsometry and VUV spectroscopy. Over the range 1.5-32 eV, the optical properties exhibit electronic transitions we assign to three groupings, E 1 , E 2 , and E 3 , corresponding to a hierarchy of interband transitions of aromatic (π → π*), non-bonding (n → π*, n → σ*), and saturated (σ → σ*) orbitals. In polystyrene there are strong features in the interband transitions arising from the side-chain π bonding of the aromatic ring consisting of a shoulder at 5.8 eV (E 1 ) and a peak at 6.3 eV (E 1 ), and from the σ bonding of the C-C backbone at 12 eV (E 3 ) and 17.1 eV (E 3 ). These E 3 transitions have characteristic critical point line shapes associated with one-dimensionally delocalized electron states in the polymer backbone. A small shoulder at 9.9 eV (E 2 ) is associated with excitations possibly from residual monomer or impurities. Knowledge of the valence electronic excitations of a material provides the necessary optical properties to calculate the van der Waals-London dispersion interactions using Lifshitz quantum electrodynamics theory and full spectral optical properties. Hamaker constants and the van der Waals-London dispersion component of the surface free energy for polystyrene were determined. These Lifshitz results were compared to the total surface free energy of polystyrene, polarity, and dispersive component of the surface free energy as determined from contact angle measurements with two liquids, and with literature values. The Lifshitz approach, using full spectral Hamaker constants, is a more direct determination of the van der Waals-London dispersion component of the surface free energy of polystyrene than other methods.

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Section: Present Workmentioning

confidence: 99%

Optical Properties and van der Waals - London Dispersion Interactions of Polystyrene Determined by Vacuum Ultraviolet Spectroscopy and Spectroscopic Ellipsometry

et al. 2007

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“…Our work is similar to that of Jones et al [5], except that their films were prepared by RF sputtering. Our AlN films were grown using MBE on low-resistivity Si (111), cut 3° off towards (110), at 860°C with ammonia as the nitrogen source, therefore they might contain some hydrogen or silicon, which tend to reduce n. Because of the high affinity of AlN for oxygen, contamination with oxygen is a possibility [4], which would also reduce the value of n. Infrared transmission measurements of AlN on high-resistivity two-side polished Si are planned to determine the impurity content.…”

Section: Introductionmentioning

confidence: 64%

“…Much of the early results are based on pioneering work by Slack, who synthesized high-purity AlN single-crystals and studied their properties, particularly the high thermal conductivity [2,3]. Recent interest in AlN has shifted to thin films prepared on different substrates (Si, SiC, sapphire) using a variety of techniques, such as molecular beam epitaxy (MBE), chemical vapor deposition [4], and RF sputtering [5].…”

Section: Introductionmentioning

confidence: 99%

Dielectric Function of AlN Grown on Si (111) by MBE

et al. 1999

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We measured the ellipsometric response from 0.7-5.4 eV of c-axis oriented AlN on Si (111) grown by molecular beam epitaxy. We determine the film thicknesses and find that for our AlN the refractive index is about 5-10% lower than in bulk AlN single crystals. Most likely, this discrepancy is due to a low film density (compared to bulk AlN), based on measurements using Rutherford backscattering. The films were also characterized using atomic force microscopy and x-ray diffraction to study the growth morphology. We find that AlN can be grown on Si (111) without buffer layers resulting in truely two-dimensional growth, low surface roughness, and relatively narrow x-ray peak widths.

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“…For the purpose of VUV radiation detection, the penetration depth 1/α(λ) of diamond and AlN materials derived from [11][12][13][14][15][16][17] drops drastically to extremely small values of the order of few nanometres. As shown in Fig.…”

Section: Motivation For Utilizing a Planar Structure -Msm Photodetectorsmentioning

confidence: 99%

Recent developments of wide-bandgap semiconductor based UV sensors

BenMoussa

Soltani

Schühle

et al. 2009

Diamond and Related Materials

102

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Future missions for space astronomy and solar research require innovative vacuum ultraviolet (VUV) photodetectors. Present UV and VUV detectors exhibit serious limitations in performance, technology complexity and lifetime stability. New developments of metal-semiconductor-metal (MSM) solar-blind photodetectors based on diamond, cubic boron nitride (c-BN), and wurtzite aluminium nitride (AlN) are reported. In the wavelength range of interest, the characteristics of the MSM photodetectors present extremely low dark current, high breakdown voltage, and good responsivity. Diamond, c-BN, and AlN MSM photodetectors are sensitive and stable under UV irradiation. They show a 200 nm to 400 nm rejection ratio of more than four orders of magnitude and demonstrate the advantages of wide band gap materials for VUV radiation detection in space.

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Optical properties of AlN determined by vacuum ultraviolet spectroscopy and spectroscopic ellipsometry data

Cited by 64 publications

References 43 publications

Optical Properties and van der Waals - London Dispersion Interactions of Polystyrene Determined by Vacuum Ultraviolet Spectroscopy and Spectroscopic Ellipsometry

Optical Properties and van der Waals - London Dispersion Interactions of Polystyrene Determined by Vacuum Ultraviolet Spectroscopy and Spectroscopic Ellipsometry

Dielectric Function of AlN Grown on Si (111) by MBE

Recent developments of wide-bandgap semiconductor based UV sensors

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