Diamond films: Initial CVD growth stage using nanodiamonds as nucleation centers

Scanning electron microscopy is used to study features of a mechanism operating in the initial growth stages during the CVD of diamond films on nucleation centers representing predeposited nanodiamonds obtained by method of detonation synthesis.     

Planar microcavity containing luminescent diamond particles with embedded silicon-vacancy color centers in its active layer

A planar hybrid microcavity containing isolated diamond particles with embedded silicon-vacancy (Si-V) color centers in its active layer is fabricated by plasma-enhanced chemical vapor deposition. Distributed Bragg reflectors are produced on the basis of alternating quarter-wave a-Si_{1 ? x} C _x :H and a-SiO₂ layers. The color centers are controllably introduced from the gas phase during the course of growth of the diamond particles. A narrowing to 5 nm of the zero-phonon line at a wavelength of 738 nm and suppression of the phonon wing in the photoluminescence spectrum of the Si-V color centers are achieved.     

Chemical vapor deposition of isolated spherical diamond particles with embedded silicon-vacancy color centers onto the surface of synthetic opal

Isolated spherical diamond particles with embedded silicon-vacancy color centers are synthesized on a patterned surface of synthetic opal by chemical vapor deposition methods. The phase composition of the particles is determined and their structural and luminescence properties are studied. Prospects are discussed for the application of these particles as integrated spherical diamond microcavities, in which color centers are situated directly in the microcavities.     

Emitting a-SiO(x)(Er) films and a-SiO(x)(Er)/a-Si:H microcavities doped with Er by remote magnetron sputtering technique

We have developed the technique of growing amorphous a-SiO(x)(Er) films and a-SiO(x)(Er)/a-Si:H multilayer structures based on spatially separating the processes of the decomposition of an oxygen-silane gas mixture in an rf glow discharge plasma and remote magnetron sputtering of an Er target. This approach allows us to control independently the film deposition rate, the Er-ion concentration and its depth distribution in the film. Time-resolved photoluminescence measurements have shown that films and planar microcavities with an Er-doped active layer exhibit internal quantum efficiency for Er ion emission of ～75%. The method that we suggest is a way of producing effectively emitting microcavity structures, in which the distribution profile of emission centers coincides with that of the electromagnetic field in individual layers of the structure.     

Micro-Raman Mapping of 3C-SiC Thin Films Grown by Solid–Gas Phase Epitaxy on Si (111)

A series of 3C-SiC films have been grown by a novel method of solid–gas phase epitaxy and studied by Raman scattering and scanning electron microscopy (SEM). It is shown that during the epitaxial growth in an atmosphere of CO, 3C-SiC films of high crystalline quality, with a thickness of 20 nm up to few hundreds nanometers can be formed on a (111) Si wafer, with a simultaneous growth of voids in the silicon substrate under the SiC film. The presence of these voids has been confirmed by SEM and micro-Raman line-mapping experiments. A significant enhancement of the Raman signal was observed in SiC films grown above the voids, and the mechanisms responsible for this enhancement are discussed.     

Planar light-emitting microcavities based on hydrogenated amorphous silicon carbide

The plasma-enhanced chemical vapor deposition (PECVD) method is used to fabricate planar Fabry-Perot microcavities (MCs) with an active region emitting light at the boundary between the visible and infrared (IR) spectral ranges. The MCs comprise an α-Si_{1 ? x} C _x :H active layer with an increased carbon content and distributed Bragg reflectors (DBRs) constituted by alternating nonemitting α-Si_{1 ? x} C _x :H/α-SiO₂ layers. The active layer and the DBRs are grown in a single technological cycle. Owing to the high optical contrast and low absorption of the layers constituting the DBRs, a high Q factor of the microcavities (Q = 316) and high emission directivity from the MCs for three pairs of layers in the DBRs are achieved. The intensity of the room-temperature photoluminescence exceeds by two orders of magnitude the emission intensity of an identical α-Si_{1 ? x} C _x :H layer without DBRs. Comparison of the experimental transmittance spectra and those calculated by the transfer-matrix method with consideration for dispersion of the real and imaginary parts of the refractive index of α-Si_{1 ? x} C _x :H is used to estimate the degree of systematic deviation of the layer thicknesses in the DBRs and to determine the upper limit of the absorption coefficient in α-Si_{1 ? x} C _x :H layers.     

Growth of diamond films on crystalline silicon by hot-filament chemical vapor deposition

The effect of hot-filament chemical vapor deposition conditions on the phase composition of diamond films grown on a silicon substrate was studied. The growth conditions providing the highest content of diamond phase at a growth rate of about 1 µm/h were ascertained.     

Structure and Properties of Thin Graphite-Like Films Produced by Magnetron-Assisted Sputtering

The structural, electrical, and optical properties of thin graphite-like films produced by magnetron- assisted sputtering onto crystalline silicon and quartz at substrate temperatures in the range from 320 to 620°C are studied. From analysis of the Raman spectra, it is established that, as the substrate temperature is elevated, the crystallite size increases and the concentration of structural defects and the content of amorphous carbon in the phase composition of the films decrease. It is found that, as the substrate temperature is elevated, the maximum of the absorption intensity in the ultraviolet spectral region of the optical absorption spectra shifts to longer wavelengths and the absorption intensity in the visible and near-infrared spectral regions increases. As the deposition temperature is elevated, the conductivity of the films increases from 0.2 Ω^–1 cm^–1 at 320°C to 30 Ω^–1 cm^–1 at 620°C.     

Crystallization ability and optical and electrical properties of Ge<Subscript>10</Subscript>(Se-Te)<Subscript>90</Subscript> and Ge<Subscript>30</Subscript>(Se-Te)<Subscript>70</Subscript> chalcogenide glassy semiconductors

Chalcogenide glassy semiconductors of the ternary system Ge-Se-Te along the Ge₁₀(Se-Te)₉₀ and Ge₃₀(Se-Te)₇₀ joins have been synthesized. The crystallization ability, near-IR transmission spectra, and temperature dependence of the electrical conductivity of the alloys obtained have been studied. It is shown that chalcogenide glassy semiconductors along the Ge₁₀(Se-Te)₉₀ join have a lower softening and crystallization points compared with semiconductors belonging to the Ge₃₀(Se-Te)₇₀ join. A change in the electrical conductivity of samples by several orders of magnitude occurs upon a phase transition from the glassy to the crystalline state. Compositions of chalcogenide glassy semiconductors in the Ge-Se-Te system are found, which have α < 1 cm⁻¹ absorption coefficient at wavelengths of λ ≈ 1.5 μm and exhibit a thermally induced phase transition from the glassy to the crystalline state.     

Ge-Te-Se and Ge-Te-Se-S alloys as new materials for acousto-optic devices of the near-, mid-, and far-infrared spectral regions

The optical, acoustic, and acousto-optic properties of new Ge-Se-Te-S and Ge-Se-Te alloys are studied. As a result of parameter optimization, efficient acousto-optic materials transparent in a wide infrared range (λ = 1.5–18 μm) are fabricated.