Reduction of Copper Oxide Induced by 172 nm Vacuum Ultraviolet Radiation at Ambient Temperature

Oxidized copper sheets were irradiated with a xenon excimer 172 nm lamp in either air or N₂/H₂ mixture at ambient temperature. The effect of 172 nm radiation on the surface composition was investigated by x-ray photoelectron spectroscopy (XPS). XPS results indicated that the surface of the copper sheet was covered with organic compounds in addition to cupric oxides. After being exposed to 172 nm radiation in air, the content of organic compounds decreased strikingly while the cupric species remained intact. However, after being exposed to radiation in the N₂/H₂ mixture, the cupric species disappeared and the Cu 2p_3/2 binding energy shifted. In the reducing N₂/H₂ mixture, the 172 nm radiation not only eliminated the organic contaminants but also reduced the cupric oxide to metallic copper.     

Thermoelectric Properties of High-Doped Silicon from Room Temperature to 900 K

Silicon is investigated as a low-cost, Earth-abundant thermoelectric material for high-temperature applications up to 900 K. For the calculation of module design the Seebeck coefficient and the electrical as well as thermal properties of silicon in the high-temperature range are of great importance. In this study, we evaluate the thermoelectric properties of low-, medium-, and high-doped silicon from room temperature to 900 K. In so doing, the Seebeck coefficient, the electrical and thermal conductivities, as well as the resulting figure of merit ZT of silicon are determined.     

Laser diodes with several emitting regions (λ = 800–1100 nm) on the basis of epitaxially integrated heterostructures

The results of a series of studies concerned with formation of epitaxially integrated InGaAs/AlGaAs and AlGaAs/AlGaAs heterostructures with several emitting regions and with investigation of properties of laser diodes based on the above structures operating in the spectral ranges λ = 800–810, 890–910, and 1040–1060 nm are summarized. It is shown that the suggested approach to integration of individual laser structures by the method of the MOVPE epitaxy operates efficiently in fabrication of laser diodes for a wide spectral range on the basis of various types of heterostructures. This approach made it possible to efficiently increase the output power of the laser diodes practically without variation in their mass-and-dimension characteristics. The main advantages of this approach and its limitations are outlined. Epitaxial integration of two laser heterostructures made it possible to increase the differential quantum efficiency by 1.7–2.0 times, while integration of three laser heterostructures increases the differential quantum efficiency by a factor of 2.5–3.0.     

Biological Effects of 25 to 150 GHz Radiation After In Vitro Exposure of Human Fibroblasts: a Comparison of Experimental Results

In this paper, we present a comprehensive discussion of the results obtained after in vitro exposure of human fetal fibroblasts and human adult fibroblasts to pulsed radiation in a wide band between 100 and 150 GHz and to continuous wave radiation at 25 GHz. In order to assess potential effects of exposure, the genome integrity, cell cycle, cytological ultrastructure, and proteins expression were evaluated.     

Rapid Sintering of Silica Xerogel Ceramic Derived from Sago Waste Ash Using Sub-millimeter Wave Heating with a 300 GHz CW Gyrotron

In this paper, we present and discuss experimental results from a microwave sintering of a silica-glass ceramic, produced from a silica xerogel extracted from a sago waste ash. As a radiation source for the microwave heating a sub-millimeter wave gyrotron (Gyrotron FU CW I) with an output frequency of 300 GHz has been used. The powders of silica xerogel have been dry pressed and then sintered at temperatures ranging from 300°C to 1500°C. The influence of the sintering temperature on the technological properties such as porosity and bulk density was studied in detail. Furthermore, X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy have been used in order to study the structure of the produced silica glass-ceramics. It has been found that the silica xerogel crystallizes at a temperature of 800°C, which is about 200°C lower than the one observed in the conventional process. The silica xerogel samples sintered by their irradiation with a sub-millimeter wave at 900°C for 18 minutes are fully crystallized into a silica glass-ceramic with a density of about 2.2 g/cm³ and cristobalite as a major crystalline phase. The results obtained in this study allow one to conclude that the microwave sintering with sub-millimeter waves is an appropriate technological process for production of silica glass-ceramics from a silica xerogel and is characterized with such advantages as shorter times of the thermal cycle, lower sintering temperatures and higher quality of the final product.     

A novel algorithm to study the impact of the mismatch on analog building blocks: a case study in basic 35 nm CMOS amplifiers

In this paper, the context of modeling of the impact of mismatch and statistical variations on analogue circuit building blocks is emphasized. The aim is to develop a new algorithm which predicts the statistical behavior of important parameters of an amplifier including output resistance, voltage gain and trans-conductance. The relative error of standard deviation of statistical parameters will remain less than 5% compared with the most accurate Monte-Carlo (MC) simulations using atomistic library model-cards. In comparison with other models which are based on the normal distribution of parameters, the proposed model does not need this limiting presumption. On the other hand, the proposed algorithm is more efficient compared with time consuming MC atomistic simulations.     

Flexibility of p–n Junction Formation from SWIR to LWIR Using MBE-Grown Hg(1–x)CdxTe on Si Substrates

In this paper, we show the versatility of using molecular-beam epitaxy (MBE) for the growth of the mercury cadmium telluride (HgCdTe) system. Abrupt composition profiles, changes in doping levels or switching doping types are easily performed. It is shown that high-quality material is achieved with Hg_(1–x)Cd _x Te grown by MBE from a cadmium mole fraction of x = 0.15 to x = 0.72. Doping elements incorporation as low as 10¹⁵ cm⁻³ for both n-type and p-type material as well as high incorporation levels >10¹⁸ cm⁻³ for both carrier types were achieved. X-ray curves, secondary-ion mass spectrometry (SIMS) data, Hall data, the influence of doping incorporation with cadmium content and growth rate, etch pit density (EPD), composition uniformity determined from Fourier-transform infrared (FTIR) transmission spectro- scopy, and surface defect maps from low to high x values are presented to illustrate the versatility and quality of HgCdTe material grown by MBE. All data presented in this work are from layers grown on silicon (112) substrate.     

Synthesis of Ge<Subscript>1−<Emphasis Type=Italic>x</Emphasis></Subscript>Sn<Subscript><Emphasis Type=Italic>x</Emphasis></Subscript> Alloy Thin Films Using Ion Implantation and Pulsed Laser Melting (II-PLM)

Ge_1−x Sn _x thin films are interesting for all-group-IV optoelectronics because of a crossover to a direct bandgap with dilute Sn alloying. However, Sn has vanishing room-temperature equilibrium solubility in Ge, making their synthesis very challenging. Herein, we report on our attempts to synthesize Ge_1−x Sn _x films on Ge (001) using ion implantation and pulsed laser melting (II-PLM). A maximum of 2 at.% Sn was incorporated with our experimental conditions in the samples as determined by Rutherford back scattering spectroscopy. A red-shift in the Ge optical phonon branch and increased absorption below the Ge bandgap with increasing Sn concentration indicate Sn-induced lattice- and band-structure changes after II-PLM. However, ion-channeling and electron microscopy show that the films are not of sufficient epitaxial quality for use in devices.