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Non-adiabatic interacting Floquet (or dressed) states arising from the intrinsic coupling between electrons and holes with off-resonant electromagnetic radiation have been investigated for recently synthesized ultrathin gapped and anisotropic black phosphorus. Our analytical calculations were carried out for the low-energy electronic subbands near the C point. Optical dressed states for both linear and circular polarizations of the incoming radiation have been obtained and analyzed. We focus our attention on linearly polarized light with arbitrary polarization direction since this case has not been considered for dressing fields imposed on initially anisotropic structures. We have examined and compared various cases for one- and few-layer phosphorus, including massless Dirac fermions with laser tunable in-plane anisotropy. The electronic properties, such as bandgaps, Fermi velocities, and effective masses, are renormalized in a very different way compared to those for the previously studied gapped Dirac structures. More importantly, material anisotropy and angular dependence of energy dispersions could be tuned by incident polarized light in the individual direction. The interaction of electrons with photons brings out a product term for two wave vector components in energy dispersions, which leads to non-vanishing off-diagonal elements in inverse effective-mass and momentum-relaxation-time tensors and is expected to have a significant effect on the conductivities of electrons and holes. Such unique features in the band structure can be applied to new designs and fabrications of optical transistors and logic devices used in optical computers and communications. [ABSTRACT FROM AUTHOR]

The charging kinetics of holes are investigated in an uncapped Ge nanocrystal by the use of the nano-electron beam induced current technique. The charging process is studied under zero volt or under an appropriate electric field. The investigation is repeated many times on the same nanocrystal and on others in the same sample to attest of the reproducibility of the results. At 0V, the cycles of charging kinetics are superimposed and are in a steady state, but an instantaneous local and negative surface potential, established in the nanocrystal at the beginning of the kinetics, slows down the holes charging process. Under an external field, the energy band bending accentuation affects the holes charging time constants. As a result, the holes charging cycles weakly affect the electrical performance of the thin oxide as is indicated by the value of the measured local resistivity of 6×1010-1011 Ω cm, which is relatively lower than that of the thick thermal oxide. [ABSTRACT FROM AUTHOR]

The Meyer-Neldel behavior reported for the emission probabilities of electrons and holes was included in our code, replacing the gap state capture cross sections of the Shockley-Read-Hall formalisms with capture cross sections containing an exponential function of the trap energy depth. The Meyer-Neldel energies for electrons and holes are the slopes of these exponentials. Our results indicate that emission probabilities of neutral states no deeper than approximately 0.45 eV and 0.37 eV from the conduction and valence band edges, respectively, can show a Meyer-Neldel behavior only, while on the other hand, its implementation in deeper gap states makes the replication of experimental J-V curves of p-i-n solar cells and detectors impossible. The Meyer-Neldel behavior can be included in all neutral capture cross sections of acceptor-like tail states without affecting the J-V characteristics, while it cannot be included in all capture cross sections of neutral donor-like tail states and/or defect states without predicting device performances below the experimental figures, that become even lower when it is also included in charged capture cross sections. The implementation of the anti Meyer-Neldel behavior at tail states gives rise to slightly better and reasonable device performances. [ABSTRACT FROM AUTHOR]

A high sensitivity photo-detector operating in the 245 to 880 nm wavelength range is reported. It is based on a planar Metal-Oxide-Semiconductor (MOS) structure fabricated on an insulator on silicon substrate where the insulator layer comprises a double layer dielectric stack of SiO2-HfO2. The MOS detector undergoes a voltage stress process after which it exhibits a record high responsivity of 0.4 A/W at 500-600 nm and 0.1 A/W at the spectrum edges, 245 and 880 nm. The structure is significantly simpler to fabricate than P-N or P-I-N junction devices and offers a lower dark current than Metal-Semiconductor-Metal diodes. Oxygen vacancies induced in the HfO2 sub-layer by the voltage stress form the conduction paths of the photo generated carriers. The penetration, under reverse bias conditions, of holes originating in the Si depletion layer is improved under illumination since their potential barrier is lowered. The compatibility with complimentary MOS technology processes makes this new structure attractive for many applications. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the optical properties of confined electronic states in ultra-thin Al0.27Ga0.73As/GaAs/vacuum surface quantum wells by using photoreflectance spectroscopy at room temperature. Well-resolved doublet structures were found in the spectra. The energy of the features increases with decreasing well width in agreement with the predictions of a model of the transition energy between confined electron and hole states in a surface quantum well. Both the transition broadening and intensity behaviors are also well explained by the effective mass approximation theory. The offset between the un-perturbed theoretical transition energy and the experimental data has been explained by surface-state interaction effects. Moreover, the fact that the light hole ground state in the surface quantum well can be pushed out from the surface quantum well has been directly observed experimentally. [ABSTRACT FROM AUTHOR]

Hole mobility degradation has been studied in high-dose boron-implanted ultrashallow junctions containing high concentrations of boron-interstitial clusters (BICs), combining an empirical method based on the self-consistent interpretation of secondary-ion-mass spectrometry (SIMS) and Hall measurements and liquid-nitrogen (LN2) to room temperature (RT) hole mobility measurements. It has been found that BICs act as independent scattering centers which have a strong impact on hole mobility in addition to the other scattering mechanisms such as lattice and impurities scattering. A mobility degradation coefficient α has been introduced, which gives information on the mobility degradation level in the analyzed junctions. In the case of very high concentrations of BICs (containing a boron density up to 8×1014 cm-2), measured hole mobilities were found to be ∼40% lower than corresponding theoretical values. BICs dissolution through multiple Flash anneals at high temperature (1300 °C) reduces the observe mobility degradation. [ABSTRACT FROM AUTHOR]

In remote microwave plasma enhanced chemical vapor deposition processes operated at atmospheric pressure, high deposition rates are associated with the localization of precursors on the treated surface. We show that mass transport can be advantageously ensured by convection for the heavier precursor, the lighter being driven by turbulent diffusion toward the surface. Transport by laminar diffusion is negligible. The use of high flow rates is mandatory to have a good mixing of species. The use of an injection nozzle with micrometer-sized hole enables us to define accurately the reaction area between the reactive species. The localization of the flow leads to high deposition rates by confining the reactive species over a small area, the deposition yield being therefore very high. Increasing the temperature modifies nonlinearly the deposition rates and the coating properties. [ABSTRACT FROM AUTHOR]

The electronic properties of the 3d transition metal impurities titanium and chromium in crystalline germanium have been investigated by means of deep level transient spectroscopy. The metals were implanted at 90 keV and diffused deeper into the bulk during a thermal anneal at 500 °C, which yielded spectra specific for the implanted metal. It was found that Ti introduces a deep electron trap and a semishallow hole trap. For Cr one deep electron trap and three hole traps were observed. The capture cross section of the electron traps is thermally activated while three of the hole traps display electric field enhanced emission, which is in agreement with multiple-acceptor states of metal impurities on substitutional sites. It is concluded that Ti in germanium is a double acceptor, while Cr is a triple acceptor with, in addition, a donor level close to the valence band. [ABSTRACT FROM AUTHOR]

Heat assisted magnetic recording (HAMR) technique requires an optical head that can efficiently generate a subwavelength optical spot. The results of finite difference time domain simulation shows that two subwavelength rectangular holes adjacent to a metallic slit aperture make an optical spot from the slit smaller and its peak intensity higher. A subwavelength spot of 82×46 nm2 (full width at half maximum) in the recording medium is obtainable when a pair of rectangular holes is flanked adjacent to the slit aperture with a much smaller distance than the optical wavelength. This configuration provides a high transmittance of the slit aperture and a high expectation for a high controllability of both a thickness of the slit and a distance between the slit and the rectangular hole by the use of the planar process. By using a plasmon waveguide to guide light into the metallic slit aperture, a thin and efficient optical head for HAMR is achieved. [ABSTRACT FROM AUTHOR]

Photonic crystal waveguides and metallic subwavelength apertures are promising tools for light manipulation. It is possible to obtain enhanced directional beams by using these structures via coupling to surface waves. In addition, these apertures can be designed to steer such directional beams by introducing asymmetrical gratings on the output surface. In the present paper, we report directional yet off-axis beaming from subwavelength apertures at microwave frequencies. The full width at half maximum of the beam is 10° while the beaming angle is 15°. Our results show that it is possible to steer the beam by the appropriate modification of the output surface. [ABSTRACT FROM AUTHOR]

A modified electromagnetic topology (EMT) simulation scheme for the interactions of an electromagnetic wave with an aperture and with cables of an electrical system beyond the aperture is described. The modified EMT simulation scheme addresses a concept in dealing with an aperture node of the topological circuitry without having to specify the details of the entire electrical circuitry. The results of the modified EMT simulation scheme have been validated through experiments for aperture/wave interactions and the induced currents on the cable near the aperture. The aperture transfer functions, obtained for both the simulation and experimental cases, have shown the characteristic response similar to that of the high-pass filter with a cutoff frequency. The simulated and measured currents on a cable, placed behind the aperture, resulted in good agreement with each other, providing the good validation of the modified EMT simulation scheme. Under this scheme, any change in topological circuitry can be handled easily in the substructural levels without having to consider an entire system. Consequently, the effects of various types of aperture interactions on the entire system can be reinvestigated via simply remodeling of topological interaction nodes in substructural levels. [ABSTRACT FROM AUTHOR]

Wave propagation characteristics of apertures were analyzed to explain the light transmission of metallic nanoapertures. Based on Maxwell’s equations, the wave dispersion relations of wave propagation modes in nanoapertures were derived. The resonance frequency shift of the aperture and the variation of the spot size are explained with the dispersion relations. The relationship between near-field and far-field light transmission power throughput and spot size is also shown with the wave mode change predicted by the dispersion relations. [ABSTRACT FROM AUTHOR]

We have measured the forces that need to be applied quasistatically to randomly perforated rectangular aluminum plates to tear them apart. Concomitantly, for identical geometrical structures, we have carried out numerical simulations of the tearing process. The two results agree quite reasonably, and especially so for perforated area densities (P) that are rather less than the critical percolation densities. A given value of P can be achieved through various different realizations (patterns of perforations), each with a somewhat different fracture (or failure) strength F. Our results predict empirically an “expected F” [F(P)] and an expected standard deviation [root variance, S(P)] as functions of P. This enables the risk analysis of failures in plates under tensile stress, which is needed in, e.g., the estimation of the flying safety of a spacecraft subject to multiple perforations. [ABSTRACT FROM AUTHOR]

This paper investigates the sampling criterion needed to image objects within a circular ring array. The array consists of transducer elements deployed along a circular aperture at regular angular intervals. Each transducer excites waves which propagate towards the center of the array and detects outgoing fields traveling towards it. It is shown that while with conventional linear apertures the sampling criterion is dictated by the wavelength of the probing wave only, in the case of a circular aperture the sampling depends on the size of the object relative to the wavelength and its position with respect to the aperture. [ABSTRACT FROM AUTHOR]

Single InAs quantum dots embedded in a planar cavity, formed by mismatched sets of GaAs/AlAs distributed Bragg reflectors, can be a useful source of triggered polarization-entangled photon pairs. We demonstrate this with a fidelity exceeding 70% for the expected entangled state. Quantum dot based devices may therefore be of great use in quantum communications and quantum information processing. [ABSTRACT FROM AUTHOR]

We present a method that allows for deterministic coupling of charge-tunable quantum dots to high-Q photonic crystal nanocavity modes. The realization of cavity-mediated coherent coupling of two distant spins is hindered by large fluctuations in quantum dot optical (trion) transition energy and interdot separation. We show that flexible cavity design and gate-voltage-tunable trion transitions in quantum dot molecules can be used to overcome these limitations and to achieve conditional quantum dynamics of two confined spins. [ABSTRACT FROM AUTHOR]

In this invited paper of the 28th International Conference of the Physics of Semiconductors (ICPS-28), we discuss the peculiar quantum electrodynamical properties of a semiconductor microcavity system, in which a cavity photon mode is strongly coupled to an intersubband transition of a doped quantum well system. In this kind of semiconductor system, it is possible to achieve an unprecedented ultrastrong coupling regime, in which the vacuum Rabi frequency is comparable to the electronic transition frequency. We discuss the anomalous quantum properties of the quantum ground state (a squeezed vacuum) and of the intersubband cavity polariton excitations. We address the role of dissipation and point out some future perspectives concerning the investigation of quantum vacuum radiation effects induced by an ultrafast time modulation of the quantum vacuum. [ABSTRACT FROM AUTHOR]

Concentric standing waves have been spatially imaged in the near-field regime within the optical aperture of a vertical-cavity surface emitting laser (VCSEL) using a scanning near-field optical microscope. Using the microscope’s near-field collection mode and subsequent detection via a spectrometer it has been possible to design an experiment to determine the spatial location of multiple lasing modes in addition to concentric standing waves. At low injection current above threshold the standing waves influence and modulate the optical emission from multiple transverse modes. These results are discussed in relation to cavity and aperture effects, and pattern formation in VCSELs. Surface defects arising in the aperture are also seen to affect the optical output and are briefly discussed. [ABSTRACT FROM AUTHOR]

An internal shrinkage of nanocavity in silicon was in situ observed under irradiation of energetic electron on electron transmission microscopy. Because there is no addition of any external materials to cavity site, a predicted nanosize effect on the shrinkage was observed. At the same time, because there is no ion cascade effect as encountered in the previous ion irradiation-induced nanocavity shrinkage experiment, the electron irradiation-induced instability of nanocavity also provides a further more convincing evidence to demonstrate the predicted irradiation-induced athermal activation effect. [ABSTRACT FROM AUTHOR]

The asymmetric aperture geometry in vertical-cavity surface-emitting laser cavities has long been known through experiments to effectively pin the polarization state of the output laser emission. In this article, we present a theoretical explanation for the observed effects due to noncircular aperture shape. The crux of our theory is that the unequal scattering losses of the laser beam between orthogonal polarizations of the same cavity eigenmodes lead to polarization pinning. Polarization-dependent calculations for elliptic apertures show that the scattering losses are lower when the polarization mode is aligned with the longest aperture axis, in agreement with experimental observations. This imbalance in scattering losses is higher than any intrinsic gain-related polarization dependence, and we suggest that it is the determining factor for polarization selection above a few-percent asymmetry in cavity geometry. [ABSTRACT FROM AUTHOR]

We study magnetization reversal processes of in-plane magnetized (Ga,Mn)As epilayers with different hole concentrations in out-of-plane magnetic fields using magnetotransport measurements. A clear difference in the magnetization process is found in two separate samples with hole concentrations of 1020 and 1021 cm-3 as the magnetization rotates from the out-of-plane saturation to the in-plane remanence. Magnetization switching process from the in-plane remanence to the out-of-plane direction, on the other hand, shows no hole concentration dependence, where the switching process occurs via domain wall propagation. We show that the balance of <100> cubic magnetocrystalline anisotropy and uniaxial [110] anisotropy gives an understanding of the difference in the out-of-plane magnetization processes of (Ga,Mn)As epilayers. [ABSTRACT FROM AUTHOR]

We present a method which increases the versatility of molecular beam epitaxy through multiple application of a stationary shadow mask. The method is based on selected area growth in the overlap of the incidence regions of two molecular beams impinging through different apertures of the mask. The width of the overlap depends on the incidence angles of the beams which can be adjusted in situ. Size-control of CdZnSe quantum-well (QW) islands with a precision of 20 nm by varying the distance between the apertures can be obtained. Without Se beam, a minor quantity of Cd is incorporated in the matrix modulating the band-gap energy by just 5 meV. Cathodoluminescence (CL) of nanoscale QW islands shows dot-like behavior, i.e., sharp emission lines that are attributed to different excited states and a blueshift of the CL on reducing the island dimensions. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Part I. Presents a stability theory which describes the conditions under which thin films rupture. Growth of holes in the film; Determination of the size of the hole; Potential source of holes which can lead to film rupture.

Presents a moment-method formulation and solution for the problem of finding the aperture fields of a slot in a ground-plane which is fed by a parallel-plate waveguide. Equations used in evanescent electric field; Numerical solution to the waveguide-fed slot; Geometry of the parallel-plate waveguide aperture system.

Presents information on a study which investigated the diffusivity of holes in silicon as a function of temperature, field strength and field direction. Description of the Monte Carlo method; Experimental details; Results and discussion; Conclusions.

Looks at the behavior of hot hole stressed SiO2/Si interface at elevated temperature. Influence of electron injection and hydrogen on the annealing; Information on the hole detrapping process; Detailed information on an experiment which carried out; Discussion and results based on the results of the experiment.

The influence of aperture diameter on image contrast and resolution in scanning near-field optical microscopy has been investigated. Evanescent standing wave fields at glass-air interfaces were probed with well-characterized aluminum-coated fiber tips. A strong decrease in image contrast was found when the aperture diameter exceeds a critical value. Numerical simulations with the concept of an intensity transfer function using the axial component of the Poynting vector inside the probe demonstrate that this phenomenon is the result of the increasing influence of higher-order waveguide modes on power transmission through the probe. It has been shown that standing wave patterns are convenient and reliable reference devices for individual probe characterization and quantification of their resolving power. [ABSTRACT FROM AUTHOR]

Presents a study that investigated the hole transport properties of gallium antimonide with various degrees of tellurium compensation in the temperature range of 4.2-300 K. Details of the single-crystal substrates of undoped and Te-compensated p-GaSb used; Illustration of the plots of the temperature dependence of hall coefficient; Conclusions.

Presents information on a study which calculated angular spontaneous emission rates and lifetimes of erbium ions in silicon/silicon dioxide microcavities for cavity lengths close to full and half-wavelengths. Methodology of the study; Results and discussion; Conclusions.

Presents a study that investigated the quality and pumping of an electron beam by means of the inhomogeneous electrostatic field at an anode aperture using numerical simulation. Description of a simulation model; Results and discussion; Conclusion.

Presents a study which described a computational model for drilling holes with focused Gaussian laser beams. Effects of optical parameters on drilling applications; Theoretical considerations in the application of a mathematical model in drilling; Description of Beer's law of absorption.

Deals with a study which measured the hole mobilities in tri-p-tolylamine-doped polymers as functions of the polymer composition, temperature and electric field. Magnitude of the mobilities; Description of the electric field and temperature dependencies; Effect of ionization potential on hole mobility.

Presents a study which examined quasistatic magnetic field penetration through a circular aperture of a spherical shield enclosing a spherical conductor. Theory; Numerical results; Conclusion.

The origin of holes in Mg-doped InxGa1-xN films is investigated using electron paramagnetic resonance (EPR) spectroscopy. Unlike in Mg-doped GaN, the number of Mg-related acceptors in films with x between 0.021 and 0.112 decreases as the hole density increases. The EPR results indicate that the previously suggested models involving isolated acceptors or band formation cannot adequately explain hole production in InGaN. Rather, additional features such as In-induced passivating centers must be introduced. [ABSTRACT FROM AUTHOR]

We demonstrated optical properties of a one-dimensional magnetophotonic crystal (MPC) which comprises two magnetic defects built into a dielectric multilayer. This MPC with the so-called dual-cavity structure exhibited resonant transmittance and enhancement of the Faraday rotation at a designed wavelength. A double peak that is intrinsic feature of dual cavities was observed in the spectrum of the Faraday rotation. However, the peak of resonant transmission had a bell-type shape. These results are in agreement with our theoretical consideration where a structural disorder in the experimental sample was taken into account. [ABSTRACT FROM AUTHOR]

An optical technique is proposed for obtaining multiple excitation spots. Phase-matched counter propagating extended depth-of-focus fields were superimposed along the optical axis for generating multiple localized excitation spots. Moreover, the filtering effect due to the optical mask increases the lateral resolution. Proposed technique introduces the concept of simultaneous multiplane excitation and improves three-dimensional resolution. [ABSTRACT FROM AUTHOR]

In this study we present a technique to obtain ordered fct FePt particles embedded in a C matrix. FePt nanoparticles are formed inside a high-pressure sputtering cell, called a particle gun (PG), and subsequently deposited on the substrate through a small orifice. These particles have a uniform size distribution with an average particle size that can be controlled in the range of 3-10 nm by adjusting the sputtering cell pressure, power, distance between the magnetron and the orifice, and by using a liquid nitrogen cooling jacket. The particles are converted to the L1[SUB0] phase as they pass through a)specially designed heating stage, attached to the top of the PG, heated by halogen lamps, thus avoiding alloying and oxidation effects. A strong dependence of coercivity on both the particle size and temperature was observed. [ABSTRACT FROM AUTHOR]

Presents an experimental work on reflection and focusing of weak cylindrical shock waves in a liquid-filled elliptical cavity. Method of generating shocks at one focus of the cavity; Results and discussion of the experiment; Conclusion.

Presents a study that investigated the formation of bubbles and holes in hydrogenated amorphous silicon films after isochronal annealing. Details of the experiment; Results and discussion; Conclusion.

We have identified that there is a small error in the original paper by Ippolito et al. [J. Appl. Phys. 97, 053105 (2005)] and we express our thanks to the authors of the comment for bringing it to our attention. However, the comment by Sheppard and Huat [J. Appl. Phys. 100, 086108 (2006)] has misinterpretations that lead to erroneous conclusions. We disagree with the statement of the comment that the conclusions on planar interface would carry through to the case of a numerical aperture increasing lens (NAIL). Our model calculates the wave aberration and provides valuable insight to the limitations of spatial resolution in the case of NAIL imaging and its dependence on various parameters, whereas angular spectrum method is not applicable to a spherical interface. The only significant error by Ippolito et al. is limited to an incorrect plot of [uppercase_phi_synonym]040 although the correct equation is given in the article. [ABSTRACT FROM AUTHOR]

A kinetic approach is used to study the feasibility of increasing the efficiency of microactuators that use radiometric force through etching holes in a single radiometer vane. It has been shown that a radiometer that consists of small vanes is capable of producing at least an order of magnitude larger force than a single-vane radiometer that takes up the same area. The optimum gap between the vanes is found to be slightly smaller than the vane size, with the optimum Knudsen number of about 0.05 based on the vane height. [ABSTRACT FROM AUTHOR]