The Raman spectrum and particularly the scattering intensities of monoclinic $\beta\text{-Ga}_2\text{O}_3$ are investigated by experiment theory. low symmetry results in a complex dependence intensity for individual phonon modes on geometry which is additionally affected birefringence. We measured spectra polarization direction backscattering three crystallographic planes modeled these dependencies using modified tensor formalism takes birefringence into account. spectral position all 15...

Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation Christian Czekalla, Chris Sturm, Rüdiger Schmidt-Grund, Bingqiang Cao, Michael Lorenz, Marius Grundmann; Whispering gallery mode lasing in zinc oxide microwires. Appl. Phys. Lett. 16 June 2008; 92 (24): 241102. https://doi.org/10.1063/1.2946660 Download citation file: Ris (Zotero) Reference Manager EasyBib...

We report on a new mechanism of giant phase modulation. The phenomenon arises when dispersed photonic mode (slow light) strongly couples to an excitonic resonance. In such case, even small amount optically injected carriers creates potential barrier for the propagating exciton-polariton which provokes considerable shift. evidence this effect by fabricating Mach-Zehnder interferometer, modulating output intensity constructive or destructive interferences controlled optical pumping micrometric...

We report on the realization of a double barrier resonant tunneling diode for cavity polaritons, by lateral patterning one-dimensional cavity. Sharp transmission resonances are demonstrated when sending polariton flow onto device. use non-resonant beam can be used as an optical gate and control device transmission. Finally we evidence distortion profile going to high density regime, signature polariton-polariton interactions.

Molecular self-attack: According to mythology, a scorpion may sting itself death; similarly, 3-aminopropyltriethoxysilane catalyzes its own hydrolysis in the atomic layer deposition (ALD) of SiO2 thin films and nanostructures. Between 120 200 °C, growth rate is constant at 0.06 nm per ALD cycle. The are chemically optically pure. nanotubes aspect ratio 500 exhibit smooth walls accurately controlled thickness. Supporting information for this article available on WWW under...

High-quality Ga2O3 thin films in the orthorhombic κ-phase are grown by pulsed-laser deposition using a tin containing target on c-sapphire, MgO(111), SrTiO3(111), and yttria-stabilized ZrO2(111) substrates. The structural quality of layers is studied based growth parameters employing X-ray diffraction 2θ-ω scans, rocking curves, ϕ reciprocal space maps. Our exhibit superior crystalline properties comparison to deposited monoclinic β-phase at nominally identical parameters. Furthermore,...

Abstract Theoretical treatment had shown that syndiotactic propagation should be slightly favored energetically over isotactic in free radical vinyl chloride polymerization. This prediction has been confirmed experimentally by x‐ray and infrared investigations of polymers prepared at various temperatures. The initiator was a peroxide, azodiisobutyronitrile, or tri‐ n ‐butylboron, no detectable influence on the results. As polymerization temperature is lowered, number lines arcs diffraction...

The dielectric tensor of $\beta$-Ga$_2$O$_3$ was determined by generalized spectroscopic ellipsometry in a wide spectral range from $0.5\,\mathrm{eV}$ to $8.5\,\mathrm{eV}$ as well calculation including quasiparticle bands and excitonic effects. tensors obtained both methods are excellent agreement with each other the observed transitions function assigned corresponding valence bands. It is shown that off-diagonal element reaches values up $|\varepsilon_{xz} | \approx 0.30 $ cannot be...

We present a formalism for calculating the Raman scattering intensity dependent on polarization configuration optically anisotropic crystals. It can be applied to crystals of arbitrary orientation and crystal symmetry measured in normal incidence backscattering geometry. The classical tensor cannot used materials due birefringence causing within depth dependent. show that limit averaging over sufficiently large depth, observed intensities converge described by an effective given here. Full...

We apply a generalized model for the determination and analysis of dielectric function optically anisotropic materials with color dispersion to phonon modes show that it can also be excitonic polarizabilities electronic band-band transitions. take into account tensor components within Cartesian coordinate system are not independent each other but rather projections polarization dipoles oscillating along directions defined by the, non-Cartesian, crystal symmetry polarizability. The is then...

Abstract Epitaxial layers of monoclinic β‐Ga 2 O 3 were successfully grown on (0001) sapphire and ( $ \bar 1 11) As GaAs substrates using metal‐organic vapor‐phase epitaxy (MOVPE). Triethylgallium (TEGa) N used as precursors for gallium oxygen, respectively. Growth conditions could be determined, where grows epitaxially c ‐plane substrates. X‐ray diffraction (XRD) transmission electron microscopy (TEM) measurements identify a epitaxial relationship with 01) || GaAs. The observed sixfold...

The magnetotransport properties [magnetoresistance (MR) and Hall effect] of Co-doped $\mathrm{ZnO}$ films prepared by pulsed laser deposition have been investigated around the metal-insulator transition (MIT) as a function temperature (from 5 to $290\phantom{\rule{0.3em}{0ex}}\mathrm{K}$) under maximum magnetic field strength $6\phantom{\rule{0.3em}{0ex}}\mathrm{T}$. From MR behavior measured at $5\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ we conclude that MIT occurs critical electron...

Abstract Optical whispering gallery mode (WGM) resonances have been observed in zinc oxide micro‐ and nanowire cavities. Using model calculations, the experimentally spectrum was reproduced. The effect has for wire radii between 100 nm 10 µm corresponding to angular numbers from 1 about 250. used determine refractive index of wires as a function photon energy temperature. Under high excitation conditions, WGM lasing observed. Two methods calculating complex resonant modes are presented:...

Voigt points represent propagation directions in anisotropic crystals along which optical modes degenerate, leading to a single circularly polarized eigenmode. They are particular class of exceptional points. Here, we report the fabrication and characterization dielectric, microcavity based on nonpolar ZnO that implements non-Hermitian system mimics behavior natural crystals. We prove exceptional-point nature by monitoring complex-square-root topology mode eigenenergies (real imaginary...

We report on the observation of macroscopically coherent states exciton–polaritons in a ZnO-based bulk planar microcavity up to 250 K. Excitation power-dependent photoluminescence investigations show clear threshold behaviour and corresponding spectral narrowing emission for negative detunings, revealing signatures Bose–Einstein condensate. For positive no condensation occurred but from an electron–hole plasma was detected. Above interscattering phenomena condensate polaritons between...

High-quality (InxGa1−x)2O3 thin films in the orthorhombic κ-phase were grown by pulsed-laser deposition (PLD) on c-sapphire substrates as well PLD-grown κ-Ga2O3 film templates. We varied In-content 0 ≤ x 0.38 of layers using a single, elliptically segmented, and tin-doped (In0.4Ga0.6)2O3/Ga2O3 target, employing vertical continuous composition spread (VCCS) PLD-technique. A stoichiometric transfer In Ga from target to has been confirmed, suggesting that formation volatile Ga2O In2O suboxides...

Material properties of orthorhombic κ-phase (InxGa1−x)2O3 thin films grown on a c-plane sapphire substrate by pulsed-laser deposition are reported for an indium content up to x ∼ 0.35. This extended range miscibility enables band gap engineering between 4.3 and 4.9 eV. The c-lattice constant as well the bandgap depends linearly In content. For > 0.35, phase change hexagonal InGaO3(ii) cubic bixbyite structure occurred. dielectric function refractive index were determined spectroscopic...

Wurtzite zinc oxide (ZnO) has a preferential growth direction along the c-axis of hexagonal unit cell, which, especially in combination with underlying (amorphous) heterostructures, can lead to high surface roughness for ZnO layers. This poses significant challenge construction e.g. photonic waveguides or gratings. Here, we propose an efficient way smoothing surfaces after deposition using collimated beam Argon ions. Furthermore, influence this treatment at different angles incidence and...

Due to its low symmetry, $\ensuremath{\beta}$-${\mathrm{Ga}}_{2}{\mathrm{O}}_{3}$ exhibits a strongly anisotropic optical response. As result, the absorption spectra change with polarization state of incoming photons. To understand this phenomenon, here we calculate complete electromagnetic wave equation solutions as function linear angle and photon energy for using previously measured complex dielectric tensor. The significant off-diagonal terms in tensor can result nonexponential decay...

Due to their unique optical properties, 2D monolayer transition metal dichalcogenides (TMDCs) show great potential for future electronic and photonic devices, but real applications, the performance of those is still in need improvement at moment. Understanding exciton charge carrier dynamics TMDCs plays a key role device especially as devices operate under strongly nonequilibrium conditions, well fundamental understanding TMDC materials. By employing pump‐probe femtosecond time‐resolved...

The change of the polarization state an arbitrarily polarized wave in optically anisotropic medium is discussed, and cases are considered where refractive index extinction coefficient as well two eigenmodes completely degenerated. latter corresponds to propagation along a singular optical axis. It found that changes its eigenmode with lowest coefficient. Only if coefficients equal, no final reached during whole propagation. For axis, Voigt waves must be whose amplitude has spatially...

A ternary, orthorhombic κ-(AlxGa1−x)2O3 thin film was synthesized by combinatorial pulsed laser deposition on a 2 in. in diameter c-sapphire substrate with composition gradient. Structural, morphological, and optical properties were studied as function of the alloy composition. The crystallized polymorph for Al contents 0.07 ≤ x 0.46, enabling bandgap engineering from 5.03 eV to 5.85 eV. direct c-lattice constant, well, show linear dependence cation XRD measurements, especially 2θ-ω-...

Abstract In this paper, the growth of orthorhombic and monoclinic (Al x Ga 1 − ) 2 O 3 thin films on (00.1) Al by tin-assisted pulsed laser deposition is investigated as a function oxygen pressure p (O substrate temperature <?CDATA $T_\mathsf{g}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>T</mml:mi> <mml:mrow> <mml:mi mathvariant="sans-serif">g</mml:mi> </mml:mrow> </mml:msub> </mml:math> . For certain conditions, defined ≥ 580 ° C ≤...