The optical isolator made of diluted magnetic semiconductor and the isolator made of a ferromagnetic-metal/semiconductor hybrid have been developed aiming to integrate nonreciprocal optical devices, such as an optical isolator and optical circulator, into the semiconductor-made optoelectronic integrated circuits,. The Cd1-xMnxTe exhibits a huge Faraday effect and can be grown on a semiconductor substrate. For Cd1-xMnxTe waveguide with a Cd1-xZnxTe/ Cd1-xMnxTe quantum well grown on GaAs substrate we achieved a high Faraday rotation of 2000 deg/cm, a high isolation ratio of 27 dB, a low optical loss of 0.5 dB/cm, and a high magneto-optical figure-of-merit of 2000 deg/dB/kG in a wide 25-nm wavelength range. It was predicted theoretically and proved experimentally the effect of non-reciprocal loss in hybrid semiconductor/ferromagnetic metal waveguides. This effect can be use for new design of waveguide optical isolator. Because of its simplicity and technological compatibility, this design is attractive for the integration into optoelectronic integrated circuits. The magneto-optical figure-of merit of 7% was demonstrated for the AlGaAs passive optical waveguide covered by Co.

In-situ transmission electron microscopy (TEM) has developed rapidly over the last decade. In particular, with the inclusion of scanning probes in TEM holders, allows both mechanical and electrical testing to be performed whilst simultaneously imaging the microstructure at high resolution. In-situ TEM nanoindentation and tensile experiments require only an axial displacement perpendicular to the test surface. However, here, through the development of a novel in-situ TEM triboprobe, other surface characterisation experiments are now possible, with the introduction of a fully programmable 3D positioning system.

Programmable lateral displacement control allows scratch tests to be performed at high resolution with simultaneous imaging of the changing microstructure. With the addition of repeated cyclic movements, both nanoscale fatigue and friction experiments can also now be performed. We demonstrate a range of movement profiles for a variety of applications, in particular, lateral sliding wear.

The developed NanoLAB TEM triboprobe also includes a new closed loop vision control system for intuitive control during positioning and alignment. It includes an automated online calibration to ensure that the fine piezotube is controlled accurately throughout any type of test. Both the 3D programmability and the closed loop vision feedback system are demonstrated here.

Electromagnetic mode localization within photonic bandgap (PBG) crystals has been evidenced by external measurement of enhanced optical emission from quantum dots or photoemissive polymers that are placed within the structure. In this paper wavelength is decreased and photonic crystal dimensions increased to allow insertion of a loop probe in the PBG to directly measure volumetric electromagnetic fields; thereby producing a volume -frequency map of field amplitude and phase within the PBG. The unit cells of the PBG are formed from arrays of Alumina strips which are supported by surrounding acrylic supports. Electromagnetic fields of single, two and three layer PBGs are predicted and these compare well with measurement.

Field localization within the PBG and transmission coefficients of the PBG, with and without electrical perturbations, are presented. Predictions assume layered unit cells formed from sections in which translational invariance along the Z-axis is assumed forzn -1 ≤ z ≤ zn for the nth section. Periodicity implies that field X dependence can be represented as a sum of Floquet modes and field solutions are found by mode matching techniques in combination with multimode cascade matrix formalism.

Transmission coefficient is measured using a focused beam, network analyzer based system and volumetric fields within the PBG are measured using a loop probe antenna inserted between Alumina strips and moved to different positions. Measurements at 1600 frequencies over the 4-18 GHz band at each of 100 positions are made. PBG fields are calibrated to probe measurements at identical positions and frequencies but absent the PBG.

Both electromagnetic model and measurement shows field localization and effective negative or zero indexes at multiple frequencies within the 4 to 18 GHz band. Volumetric field magnitudes increase by at least one order of magnitude and local field phase-frequency derivatives are negative or near zero near localization frequencies. Field localizations and transmission are sensitive to small perturbations of electrical properties or geometry. Wideband measurements of PBGs, perturbed by small cylindrical inserts placed at high field locations, allow precision measurements of an insert’s electromagnetic properties.

Colloidal precursor solutions, obtained from a mixture of titanium isopropoxide, isopropyl alcohol and silver nitrate, were used to fabricate amorphous TiO2 and Ag/TiO2 thin films by sol-gel process. The films were deposited on borosilicate substrates, which were heated at 400 °C for 30 minutes and cooled rapidly to the formation of amorphous coatings. The films were investigated by X-ray diffraction, scanning electron microscopy, atomic force microscopy and UV-vis spectroscopy. The thickness, roughness, refraction index, and particle size of the TiO2 and Ag/TiO2 films were determined and compared. Finally, hydrophobic-hydrophilic property was evaluated to the thin films produced.

The generation of hot charge carriers within a solid bombarded by charged particles is investigated using biased thin film metal-insulator-metal (MIM) devices. For slow, highly charged ions approaching a metal surface the main dissipation process is electronic excitation of the substrate, leading to electron emission into the vacuum and internal electron emission across the MIM junction. In order to gain a deeper understanding of the distribution and transport of the excited charge carriers leading to the measured device current, we compare ion induced and electron induced excitation processes in terms of absolute internal emission yields as well as their dependence on the applied bias voltage.

The exceptional electrical, optical, and mechanical properties of graphene make it a promising material for many industrial applications such as solar cells, semiconductor devices, and thermal heat sinks. However, the greatest obstacle in the use of graphene in industry is high-throughput scaling of its production and characterization. Chemical-vapor deposition growth of graphene has allowed for industrial-scale graphene production. In this work we introduce complimentary high-throughput metrology technique for characterization of chemical-vapor deposition-grown graphene. This metrology technique provides quick identification of thickness and uniformity of entire large-area chemical-vapor deposition-grown graphene sheets on a glass substrate and allows for easy identification of folds and cracks in the graphene samples. This metrology technique utilizes fluorescence quenching microscopy, which is based on resonant energy transfer between a dye molecule and graphene, to increase allow graphene visualization on the glass substrate and increase the contrast between graphene layers.

We describe an ex-situ monitoring technique for a small amount (∼30 mono-layers) of erbium monoantimonide (ErSb) deposited on an indium antimonide (InSb) epitaxial layer prepared on InSb(100) substrates by metal organic chemical vapor deposition (MOCVD). Our objective is to improve thermoelectric properties of nanocomposites that employ nanometer size semi-metallic ErSb particles (ErSb nanoparticles) embedded in ternary group III-V compound semiconductor host materials such as indium gallium antimonide (InGaSb) and indium antimonide arsenide (InSbAs). The formation of ErSb nanoparticles embedded in a host material is spontaneous and needs to be carefully controlled to tune the size and volume density of the ErSb nanoparticles. We used an ex-situ monitoring technique based on glancing-angle infrared-absorption, reflection absorption infra-red spectroscopy (RAIRS), to study the formation of ErSb nanoparticles to correlate the amount of delivered ErSb and surface morphology of the surface of InSb covered with ErSb.

Internal friction (IF) of a metallic glass Zr55Cu30Al10Ni5 has been measured near the glass transition temperature T g (= 666 K). The measurement is performed by using DMA (TA Instrument) apparatus at a frequency of 0.01 Hz for a specimen stabilized by annealing. The specimen is kept at a constant temperature T, and the IF value Q -1 is measured as a function of time t. A fluctuation of Q -1 with time is seen, and the magnitude of the fluctuation, F(t), is derived from the Q -1-vs-t data. F(t) is Fourier transformed to the frequency spectrum F(f). Such experiment and analyses are carried out at various temperatures near T g. A characteristic peak (f ~ 10-3 Hz) is found in the spectrum F(f) in the glass transition region.

In this work, we report on the microstructural and morphological characterization of III-V semiconductor nanowires (NWs) epitaxially grown on (111)B-GaAs substrates by Au-catalyst assisted metalorganic vapor phase epitaxy. As-grown dense (108-109 cm-2) arrays of few-micron long vertically-aligned (i.e. parallel to the <111> crystallographic axis) GaAs, AlxGa1-xAs and core-shell GaAs-AlxGa1-xAs NWs were investigated, carrying out HRXRD measurements on different (hkl) reflections and by recording reciprocal space maps (RSMs) around the materials (111) reciprocal lattice points (relps). We show that NW diffraction peaks are visible in the RSM by means of characteristic halos. In the case of GaAs NWs, the halo is located at the (111) relp indicating that the NWs are grown along the <111> direction and parallel to the <111> axis of the GaAs substrate. On the contrary, for AlxGa1-xAs NWs or intentional core-shell GaAs-AlxGa1-xAs NWs the halo is displaced (along the momentum transfer normal to the surface, Qz) with respect to the GaAs (111) relp due to the elastic lattice strain associated with the compositional variation, e.g. the Al molar fraction in the AlxGa1-xAs alloy, within the nanostructures.

With the event of nanotechnology, the field of thermoelectric (TE) materials has been re-invigorated with many recent advances towards materials with high thermoelectric efficiency (dimensionless figure of merit, ZT). The realization of such materials opens up new avenues to the creation of devices that can be used in freon-less refrigeration, micro-electronic cooling, or for harnessing lost heat energy from sources such as car engines. In our own research work, we have successfully devised a synthetic technique towards nanoparticles composed of bismuth, antimony, and tellurium that has proven highly versatile in tuning both the composition and shape/structure of the resulting nanoparticles. The ability to control the nanoparticle composition and shape/structure are highly important as these are critical parameters that dictate the resulting devices TE activity. In a modified polyol synthetic technique, it was found that many complex composition, shape, and structure combinations could be obtained for the nanoparticles including Bi-Sb nanodiscs with controllable size, a heterostructure composed of Sb2Te3 nanodiscs deposited on Te nanowires, or small particles deposited on a (Bi0.5Sb0.5)2Te3 wire, just to name a few. By simply changing the capping ligands used in the synthesis, the nanoparticles resulting composition, morphology and structure could be changed, leading to a straightforward route towards TE nanoparticles with interesting properties. This presentation focuses on our recent study of the synthesis of bismuth, antimony, and tellurium composite nanoparticles with applications in thermoelectric materials in terms of understanding the underlying mechanisms of the synthetic technique, and characterization of the resulting nanomaterial properties.

When an electrocatalyst, platinum, was coated on ionic-polymer gel surfaces and was immersed into an acidic formaldehyde solution, an input dc current will produce oscillatory ac on the surfaces of the ionic-polymer-metal-composites(IPMC), which eventually causes self-oscillatory bending of the actuators. Typical IPMC actuators have a large length-to-height ratio, exhibiting large deformation during bending and relaxation processes. A multiphysics modeling of self-oscillations of IPMC actuator was carried out, incorporating the electrochemical oscillations, electrokinetics, electrostatics and nonlinear large deformation of the actuators.

The surface and interface of SiGe layers on Si were found to incur drastic changes during layer rapid growth and post-growth rapid annealing. As deposited and thermal annealed samples were characterized using Energy dispersive X-ray Analysis (EDX) enhanced by Monte Carlo simulation for precise evaluation of Ge concentration. X-ray Diffraction (XRD) data exhibited a small shift of the SiGe (400) peak towards low 2θ values, which was attributed, primarily, to change in the Ge concentration. Confocal Raman Spectroscopy of samples showed regions of high and low strain that resulted from fluctuations in Ge concentrations. Nano- and submicronpyramidal features at the surface of Si1-xGex layers (x=17% and 28%) were revealed by Atomic Force Microscopy (AFM) and SEM. Additionally, pyramidal nanodots were revealed for [Ge]=17% samples and high density nanostructure for 28% appeared along the crosshatch strain pattern induced by misfit dislocations, when annealed at 700°C and 900°C, respectively. The observed Ge-rich nano-features, which were obtained with low thermal budget low cost techniques, are expected to be useful for bandgap engineering and third generation solar cells.

Be and Mg co-doped ZnO films Zn1-x-yBexMgyO (0 ≤ x ≤ 0.10, 0 ≤y ≤ 0.20) have been deposited for the first time by novel chemical deposition or spin coating method. From the x-ray diffraction patterns it is noticed that the pristine ZnO film exhibits wurtzite polycrystalline structure, however, co-doped films are (0002) preferentially oriented. The (0002) peak intensity also increases with the corresponding increase in dopants concentrations. The systematic decrease in the c-axis lattice parameter value in the co-doped films as compared to pure ZnO film suggests the incorporation of smaller ions Be+2/Mg+2 at Zn+2 site. From the optical transmittance measurement it is noticed that all the films exhibited almost 80% transmittance in the visible region with sharp and single absorption edges in the UV region. The cut-off wavelength shifts from 375nm for the ZnO film to 330nm with 10 Be and 20% Mg co-doped film. The bandgap calculations revealed an increase in bandgap from 3.26eV (ZnO) to 3.60eV (Zn0.7Be0.1Mg0.2O) film. Such an increase in the co-doped films fabricated by a much simpler and cheaper process is very useful in the realization of UV radiation detection without having little interference from the visible light.

In this work a microscopic Hamiltonian is investigated using the Hubbard model for a ferromagnet with two degenerate bands, taking into account the Jahn-Teller effect. A macroscopic free energy is obtained from the microscopic Hubbard Hamiltonian. All free energy coefficients depend on microscopic parameters: temperature T and composition x. As a result of analytical minimization of free energy, phase diagrams are numerically constructed. It is shown that at certain values of parameters on the phase diagrams there are thermodynamic paths which correspond to experimentally observed sequences of phase transitions. Using density of states spectra for different compositions x the T-x phase diagram is numerically constructed. This phase diagram can theoretically explain experimentally observed behavior of the temperatures of phase transitions.

On-chip MEMS (Micro Electromechanical Systems) characterization devices have been used to extract the Young’s modulus and average stress of polysilicon doped with phosphorus using thermal diffusion from a spin-on-dopant source. A customized fabrication process was developed and the devices were fabricated and tested. Resonant and static deformation tests were performed using microbridges. Information gathered from these experiments was combined to extract the Young’s modulus and residual stress of the thin film. Several doping concentrations, from undoped to 2.99×1020 phosphorus atoms/cm3 (4.148×10-4 Ω/cm), have been studied and it has been concluded that the Young’s modulus of phosphorus doped polysilicon with a chemical phosphorus concentration of 1.96×1020 atoms/cm3 (4.572×10-4 Ω/cm) increases by approximately 50GPa and the average stress of polysilicon with a phosphorus concentration of 2.99×1020 atoms/cm3 (4.148×10-4 Ω/cm) becomes more tensile by approximately 63 MPa relative to undoped specimens.

The fabrication and characterization of thin-film silicon bulk resonators processed on glass substrates is described. The microelectromechanical (MEMS) structures consist of surface micromachined disk resonators of phosphorous-doped hydrogenated amorphous silicon (n+-a-Si:H) deposited by radiofrequency plasma enhanced chemical vapour deposition (RF-PECVD). The devices are driven into resonance by electrostatic actuation and the vibrational displacement is detected optically. Resonance frequencies up to 30 MHz and quality factors in the 103-104 range in vacuum were measured. A high density of modes that increases with resonator diameter was observed. Membrane-like vibrational modes show good agreement with finite element simulations. The effect of geometrical dimensions of the disks on the resonance frequency was also studied. When operated in air higher harmonic modes show increasing quality factors.

We use a group theoretical approach to model the nitrogen-vacancy defect in diamond. In our analysis we clarify several properties of this defect that have been source of controversy such as the ordering of the singlets and the mechanism that leads to spin mixing in the excited state of this defect. In particular, we demonstrate that the ordering of the ground state configuration (e2) is {3A2, 1E, 1A1} and that the spin-spin interaction causes the mixing in the excited state. In addition, we analyze the angular momentum and spin properties of the excited state structure that enables a spin photon entanglement scheme that has been recently demonstrate experimentally. Our description is general and it can be easily applied to other defects in solid-state systems.

The electrowetting equation predicts contact angle modulation to zero degrees as voltage is continually increased. However, in practice contact angle appears to saturate around 60 to 70°. Although several hypotheses have been advanced to explain the physical mechanisms of contact angle saturation, none satisfactorily and unequivocally holds for the large body of electrowetting data. Herein we experimentally demonstrate that under DC voltage electrowetting contact angle saturation is invariant to polymer, fluid, and interfacial materials properties. We furthermore reveal that saturation is also a time-dependant phenomenon.

The composition of Cu2ZnSnS4 thin-film solar cell absorbers was varied to induce the.formation of secondary impurity phases. For their identification, the samples have been investigated by Cu L3 and S L2,3 soft x-ray absorption (XAS) spectroscopy. We find that Cu L3 XAS is especially sensitive to the presence of copper sulfides as well as copper oxides and/or changes in the electron configuration, suggesting a basis for future studies of the surface, defect, and interface characterization of similar samples. Additionally, it is shown that the S L2,3 absorption data can be used as a very sensitive probe of the variations in the prevalence of S-Zn bonds in the near-surface region of the investigated samples.