Surface morphology, structural and optical properties of CuInS2 thin films grown by the single source thermal evaporation in vacuum have been studied. The films were annealed from 250 to 550 °C in argon atmosphere with low oxygen concentration (O2 < 2 ppm). CuInS2 films are characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and optical transmittance and reflectance spectra. The maximum grain size of the sample after annealing at 550 °C was over 150 nm. The electron dispersion spectroscopy and X-ray analysis concludes that the polycrystalline CuInS2 thin film after annealing above 200 °C were sulphur-poor. We obtain CuInS2 layers with high structural and optical quality at annealing temperature above 450 °C with formation of In2O3 as minority phase. The band gap energy of the CuInS2 films after annealing above 450 °C was about 1.50 eV which perfectly matches the solar spectrum for energy conversion.

For red, green and blue OLEDs that emit for each of them in a wide spectral range ($\Delta \lambda \approx 200$ nm), we calculate the luminous luminance, the energetic luminance and the various yields in the pseudo-monochromatic hypothesis (ideal source generally considered), and we compare with a calculation in relation with a polychromatic system (real source). Finally, we demonstrate that the values of the energetic luminance and of the energetic or quantum yield are practically unchanged whatever the hypothesis; on the contrary, in the simplified case of the pseudo-monochromatic source, the luminous luminance and the luminous yield of a green organic diode are overvalued in relation to the polychromatic real case, whereas for a blue or a red organic diode these parameters (calculated in the pseudo-monochromatic hypothesis) are undervalued. The error is all the more great since the OLED emission is far away from the maximum value of the photoptical eye response.

A high-performance InP/InGaAs $\delta $-doped pnp heterojunction bipolar transistor (HBT) has been first fabricated and demonstrated. The addition of a $\delta $-doped sheet between two undoped spacer layers effectively eliminates the potential spike at emitter-base junction, lowers the emitter-collector offset voltage, and increases the barrier for electrons, simultaneously. Experimentally, a maximum current gain of 50 and a low offset voltage of 70 mV are obtained, respectively. To our knowledge, the offset voltage of the studied device is the lowest value for the reported InP/InGaAs pnp HBTs.

The substitution sites of Pb and Dy dopants in the cuprate-type high temperature superconductor Bi2Sr2Ca1Cu2O$_{8+\delta}$ are determined by a direct comparison of the angle-scanned X-ray photoelectron diffraction (XPD) patterns. We demonstrate the power of XPD as a fingerprinting tool and conclude that Pb occupies Bi sites and Dy the Ca sites. The presence of the incommensurate lattice modulation is not visible in XPD, probably due to a Pb-induced, reduced modulation amplitude.

The different types of errors affecting the spectral purity of a rapidly chirped continuous wave laser are experimentally studied using an unbalanced interferometer. The response of the interferometer to the deterministic (periodic and aperiodic) and stochastic quantum and technical laser frequency noises is theoretically analysed and experimentally investigated with an external cavity diode laser operating at 793 nm and providing chirps in excess of 10 GHz on the ms timescale. The system is shown to be able to measure the laser frequency to better than 1 MHz during the chirp. It provides an error signal that can be used to servo-control the laser frequency in real time while it is chirped.

The novel VCP system is a mobile physical deposition method to deposit metallic/magnetic films using various source materials including powder, lump, pre-alloyed ingots and wires. The VCP system consists of a large deposition area of 960 cm2 and has been used for the first time to prepare magnetic thin films of Si3Fe97. The source material evaporated by a resistively heated furnace, which was position right under the substrate within the VCP system, contains small pieces of conventional 3% silicon-iron steel as source materials. The magnetic analysis of the films was achieved by using a vibrating sample magnetometer (VSM). Observations indicate that the magnetic anisotropy and coercivity are dependent on the type of substrate and the deposition conditions. Results of all films deposited on flexible kaptonTM are anisotropic in the film plane whereas the films deposited on glass substrate indicate the less-well defined anisotropy in the film plane while the substrate holder of the VCP system was run at the speed of 100 rpm. In the case of stationary magnetic materials production, the films deposited on kapton and glass substrates show isotropic magnetic behaviour. All films showed planar magnetic anisotropy irrespective of type of substrate and the production conditions used. The findings are discussed in terms of scaling up the technique for the possible production of various shapes of circular, square or strip components with the compositions equivalent to that of conventional electrical steels in order to investigate a possible future to produce large scale of silicon-iron as the core materials for rotating machines and power transformers.

We present results on the room temperature mechanical quality factor of single crystal calcium fluoride (CaF2) grown by the Bridgman-Stockbarger method. Resonant mode Q-factors are measured in the frequency range 20 to 76 kHz using tungsten wire loop suspensions. In spite of indications of only moderate crystal purity, we observed 6 modes with Q-factor > 107, and one with $Q = 4.5 \times 10 ^{7}$, more than an order of magnitude higher than previously reported results.

Nanowires of antimony (Sb) with diameters ranging from 90 down to 20 nm have been synthesized by electrodeposition within nanoporous polycarbonate membrane. The salient point of the present work is the detailed examination of each wire individually giving evidence of their good quality. The growth morphology, crystalline quality as well as chemical composition of individual nanowires were carried out by combination of various transmission electron microscopy (TEM) techniques. They are single crystals and have homogeneous cylindrical shape. However, a distribution of wire diameters and a roughness of few nanometers on the wire surface have been observed. Chemical analyses using electron energy loss spectroscopy (EELS) confirmed the purity of electrodeposited Sb nanowires, but revealed the existence of an oxidized layer (≤2 nm in width) surrounding the wires.

The impedance of a positive column has been calculated at medium pressures i.e. at the regime of step ionization-ambipolar diffusion. Calculations were carried out for two cases: (a) metastable level decay by electron impact; (b) metastable level decay on the walls as a result of diffusion. In both cases the impedance has generally an inductive character. In the case of metastable level decay by electron impact, the impedance curve starts from the coordinate origin at $\omega =0 $. At low frequencies the PC has a negatron property, while the static volt-ampere characteristics of the stationary PC becomes parallel to the current axis. The module |Z| reaches its maximum value at frequencies of about the order of $\sqrt{ \tau_a^{-1}\alpha _{m}n_{0}}$. At very high frequencies $\omega \longrightarrow \infty $, the impedance reaches the real value of $Z=R_{0}$. In the case when metastable levels decay as a result of diffusion, the impedance curve starts from the negative real values at $\omega=0$. The volt-ampere characteristics of the stationary PC drops. The module |Z| reaches its maximum value at frequencies of about the order of $\sqrt{\tau_a^{-1} \tau^{-1}_{m}}$. At very high frequencies $\omega \longrightarrow \infty $, the impedance reaches the real value of $Z=R_{0}$. In both cases, impedance curves have single structured shapes in spite of existence of several characteristic time scales of different order.

At National Metrology Institute of Turkey (UME, Ulusal Metroloji Enstitüsü), luminous intensity unit of candela was realized using detector-based approach and photometric scale was re-established depending on this new realization. Candela was measured on photometric bench using interferometric distance measurement system and filter-radiometer traceable to UME primary level electrical-substitution cryogenic radiometer. Thermally stabilized filter radiometer, which has been designed for spectral irradiance measurements, is consists of trap detector, filter housing and precision aperture. Different measurement techniques were used to fully characterize each parameter of filter-radiometer; like effective aperture area, spectral transmittance of $V(\lambda)$ filter and responsivity of trap detector.

The final properties of cast materials depend greatly on the solidification process undergone by the material. In this paper, we study gold alloys dedicated to the watch industry and jewellery in the framework of a research collaboration with the Metalor Company. The aim is to improve the concentration homogeneity of the ingots by controlling the solidification step. It can be achieved by reducing segregations by a decrease in the grain size. For this purpose, we set up a multiphase electromagnetic stirring of the melt to favour the growth of finer grains and improve the homogeneity of the composition. We first design an electromagnetic stirrer by numerical simulation. The stirrer is then implemented on a model experiment. Eventually, the alloys are characterised by metallography and etching to evidence the grain structure. As expected, we obtain a substantial reduction of the grain size although, some work remains to be done to attain the final goal of even finer grains.