Strong second-harmonic response from semiconductor-dielectric interfaces.

In this study, an analysis of the second-harmonic generation (SHG) response from surfaces containing dielectric-semiconductor interfaces with sub-wavelength features is presented. The investigated medium is a metamaterial where the SHG response is governed by the symmetry breaking between consecutive layers. The examined material is composed of a periodic structure based on 50 nm silicon nitride and 10 nm indium gallium zinc oxide (IGZO) fabricated on a quartz glass substrate. The elementary cell consists of a pair of materials in an exchangeable order. The preliminary results show a promising application of the amorphous IGZO as a nonlinear optical material, whose optical characteristics can be controlled by the fabrication process itself. Prepared structures give a remarkably high SHG response. For an effective thickness of the structure equal to 240 nm, a more than 250-fold increase in SHG compared to the reference substrate is observed.

450 nm (Al,In)GaN optical amplifier with double 'j-shape' waveguide for master oscillator power amplifier systems.

In this paper we demonstrate 450 nm (Al,In)GaN graded index separate confinement heterostructure travelling wave optical amplifier with a double 'j-shape' waveguide. The length of the amplifier is 2.5 mm and the width of the ridge is 2.5 µm. The active region consists of three 3.5 nm thick quantum wells. The measured optical gain under CW operation in room temperature exceeded 29 dB for low power input signals. The saturation output power was 21 dBm for 400 mA driving current. The demonstrated amplifier, provides a good solution for the blue light, all nitrides, and master oscillator power amplifier systems.

['How strange is the patient to me?'] / "Wie fremd ist mir der Patient?".

'How strange is the patient to me?' Physicians' attitudes and expectations toward treating patients with a migration background Objectives: Undergraduate and postgraduate training in cultural competence remains a challenging issue. It might be useful to integrate culturally sensitive learning objectives in existing curricula. As part of a needs assessment, this qualitative study examined the prototypical experiences in clinical routines with patients with a migration background. METHODS: Twenty physicians took part in half-structured narrative interviews, which were then analyzed by linguistic-ethnographic conversation analysis. RESULTS: The main reasons for difficulties in patient-physician relation proved to be language barriers. Assignments of professional interpreters were rated critically. Physicians attributed the responsibility for successful communication mainly to the patient. The physicians saw little need for training in cultural competence. CONCLUSIONS: The integration of learning objectives related to cultural sensibility in existing curricula would seem to be useful, especially because the physicians interviewed reported little need for additional training on their own. The importance of implied negative attitudes and stereotypes in creating a culturally sensitive approach should be taken into account.

Studies of Electrical Parameters and Thermal Stability of HiPIMS Hafnium Oxynitride (HfOxNy) Thin Films.

This work demonstrated the optimization of HiPIMS reactive magnetron sputtering of hafnium oxynitride (HfOxNy) thin films. During the optimization procedure, employing Taguchi orthogonal tables, the parameters of examined dielectric films were explored, utilizing optical methods (spectroscopic ellipsometry and refractometry), electrical characterization (C-V, I-V measurements of MOS structures), and structural investigation (AFM, XRD, XPS). The thermal stability of fabricated HfOxNy layers, up to 800 °C, was also investigated. The presented results demonstrated the correctness of the optimization methodology. The results also demonstrated the significant stability of hafnia-based layers at up to 800 °C. No electrical parameters or surface morphology deteriorations were demonstrated. The structural analysis revealed comparable electrical properties and significantly greater immunity to high-temperature treatment in HfOxNy layers formed using HiPIMS, as compared to those formed using the standard pulsed magnetron sputtering technique. The results presented in this study confirmed that the investigated hafnium oxynitride films, fabricated through the HiPIMS process, could potentially be used as a thermally-stable gate dielectric in self-aligned MOS structures and devices.

Investigations of Structural and Electrical Properties of ALD Films Formed with the Ozone Precursor.

The continuous development of ALD thin films demands ongoing improvements and changes toward fabricating materials with tailored properties that are suitable for different practical applications. Ozone has been recently established as a precursor, with distinct advantages over the alternative oxidizing precursors in the ALDs of advanced dielectric films. This study reports alumina (Al2O3) and hafnia (HfO2) formation using an O3 source and compares the obtained structural and electrical properties. The performed structural examinations of ozone-based materials proved homogenous high-k films with less vacancy levels compared to water-based films. The enhanced structural properties also result in the problematic incorporation of different dopants through the bulk layer. Furthermore, analysis of electrical characteristics of the MIS structures with ALD gate dielectrics demonstrated the improved quality and good insulating properties of ozone-based films. However, further optimization of the ALD technique with ozone is needed as a relatively low relative permittivity characterizes the ultra-thin films.

Refractive Index of Heavily Germanium-Doped Gallium Nitride Measured by Spectral Reflectometry and Ellipsometry.

Gallium nitride (GaN) doped with germanium at a level of 1020 cm-3 is proposed as a viable material for cladding layers in blue- and green-emitting laser diodes. Spectral reflectometry and ellipsometry are used to provide evidence of a reduced index of refraction in such layers. The refractive-index contrast to undoped GaN is about 0.990, which is comparable to undoped aluminium gallium nitride (AlGaN) with an aluminium composition of 6%. Germanium-doped GaN layers are lattice-matched to native GaN substrates; therefore, they introduce no strain, cracks, and wafer bowing. Their use, in place of strained AlGaN layers, will enable significant improvements to the production process yield.

Silicon-Carbide (SiC) Nanocrystal Technology and Characterization and Its Applications in Memory Structures.

Colloidal cubic silicon-carbide nanocrystals have been fabricated, characterized, and introduced into metal-insulator-semiconductor and metal-insulator-metal structures based on hafnium oxide layers. The fabricated structures were characterized through the stress-and-sense measurements in terms of device capacitance, flat-band voltage shift, switching characteristics, and retention time. The examined electrical performance of the sample structures has demonstrated the feasibility of the application of both types of structures based on SiC nanoparticles in memory devices.

Effect of Sample Elevation in Radio Frequency Plasma Enhanced Chemical Vapor Deposition (RF PECVD) Reactor on Optical Properties and Deposition Rate of Silicon Nitride Thin Films.

In this paper we investigate influence of radio frequency plasma enhanced chemical vapor deposition (RF PECVD) process parameters, which include gas flows, pressure and temperature, as well as a way of sample placement in the reactor, on optical properties and deposition rate of silicon nitride (SiNx) thin films. The influence of the process parameters has been determined using Taguchi's orthogonal tables approach. As a result of elevating samples above the electrode, it has been found that deposition rate strongly increases with distance between sample and the stage electrode, and reaches its maximum 7 mm above the electrode. Moreover, the refractive index of the films follows increase of the thickness. The effect can be observed when the thickness of the film is below 80 nm. It has been also found that when the deposition temperature is reduced down to 200 °C, as required for many temperature-sensitive substrate materials, the influence of the substrate material (Si or oxidized Si) can be neglected from the point of view of the properties of the films. We believe that the obtained results may help in designing novel complex in shape devices, where optical properties and thickness of thin plasma-deposited coatings need to be well defined.