Laser-Rf double-resonance studies of the hyperfine structure of metastable atomic states of55Mn

The hyperfine structure (hfs) of the metastable atomic states 3d⁶4s⁶ D _{1/2, 3/2, 5/2, 7/2, 9/2} of⁵⁵Mn was measured using theABMR- LIRF method (atomicbeammagneticresonance, detected bylaserinducedresonancefluorescence). The hfs constantsA andB, corrected for second order hfs perturbations, could be derived from these measurements. The theoretical interpretation of these correctedA- andB-factors was performed in the intermediate coupling scheme taking into account the configurations 3d ⁵4s ², 3d ⁶4s and 3d ⁷. Examining the influence of the composition of the eigenvectors on the hfs parameters \(\left\langle {r^{ - 3} } \right\rangle ^{k_s k_l } \) it was found, that for the configuration 3d ⁶4s the two-body magnetic interaction should be considered in the calculation of the eigenvectors. Investigating second order electrostatic configuration interactions and relativistic effects and using calculated relativistic correction factors we obtained for the nuclear quadrupole moment of the nucleus⁵⁵Mn a value ofQ=0.33(1) barn, which is not perturbed by a shielding or antishielding Sternheimer factor. The following hfs constants have been obtained: $$\begin{gathered} A\left( {{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}} \right) = 882.056\left( {12} \right)MHz \hfill \\ A\left( {{3 \mathord{\left/ {\vphantom {3 2}} \right. \kern-\nulldelimiterspace} 2}} \right) = 469.391\left( 7 \right)MHzB\left( {{3 \mathord{\left/ {\vphantom {3 2}} \right. \kern-\nulldelimiterspace} 2}} \right) = - 65.091\left( {50} \right)MHz \hfill \\ A\left( {{5 \mathord{\left/ {\vphantom {5 2}} \right. \kern-\nulldelimiterspace} 2}} \right) = 436.715\left( 3 \right)MHzB\left( {{5 \mathord{\left/ {\vphantom {5 2}} \right. \kern-\nulldelimiterspace} 2}} \right) = - 46.769\left( {30} \right)MHz \hfill \\ A\left( {{7 \mathord{\left/ {\vphantom {7 2}} \right. \kern-\nulldelimiterspace} 2}} \right) = 458.930\left( 3 \right)MHzB\left( {{7 \mathord{\left/ {\vphantom {7 2}} \right. \kern-\nulldelimiterspace} 2}} \right) = 21.701\left( {40} \right)MHz \hfill \\ A\left( {{9 \mathord{\left/ {\vphantom {9 2}} \right. \kern-\nulldelimiterspace} 2}} \right) = 510.308\left( 8 \right)MHzB\left( {{9 \mathord{\left/ {\vphantom {9 2}} \right. \kern-\nulldelimiterspace} 2}} \right) = 132.200\left( {120} \right)MHz \hfill \\ \end{gathered} $$      

Renormalized perturbation theory of the Van der Pol oscillator

The renormalized perturbation expansion for the linewidth of the Van der Pol oscillator is extended to fifth order. The results of the previously obtained fourth order are thereby improved for pump strengthsa5. No indication of a breakdown of the expansion, even for strong pumping, is found.     

Infrared and Raman study of Si2Te3

Results of ir and Raman investigations on trigonal layer-structured Si₂Te₃ single crystals are reported. The ir reflection spectrum withEc exhibits seven reststrahl-like bands, whereas the corresponding spectrum withEc shows only one very small bump. Values for ₀ and are given. The Raman spectra are very rich in structure and can only be interpreted qualitatively as being a mixture of single phonon lines and one- and two-phonon density-of-states contributions. One-phonon density-of-states effects are disorder-induced owing to the statistical occurrence of the Si atoms within the regular hexagonal Te sublattice.     

Stable mode-locked operation up to 80 /spl deg/C from an InGaAs quantum-dot laser

We demonstrate the mode-locked operation of a two-section quantum-dot laser in a broad temperature range. Stable mode-locking was observed at temperatures ranging from 20 /spl deg/C to 70 /spl deg/C, with signal-to-noise ratios well over 20 dB and a -3-dB linewidth smaller than 80 kHz. In the temperature range between 70 /spl deg/C and 80 /spl deg/C, the mode-locking was less stable. It was found that in order to provide stable mode-locked operation with increasing temperature, the reverse bias on the absorber section must be reduced accordingly.     

Analysis of temperature-dependent optical gain in GaN-InGaN quantum-well structures

The temperature dependent spectral gain in InGaN-GaN multiple quantum-well structures with 10% In content is investigated. Mode gain is measured in a temperature range between 239 K and 312 K using the Hakki-Paoli technique and compared to simulations. The simulation accounts for temperature-dependent polarization dephasing, and hence homogeneous broadening, in a rigorous fashion, without any fit parameter. It is found that the evolution of the gain spectrum with temperature at different drive currents can be modeled using a temperature-independent single value for inhomogeneous broadening. The resulting compositional fluctuations are compared to structural measurements.     

Shielding Effectiveness Data on Commercial Thermoplastic Materials

Ten different commercially available conductive thermoplastic materials have been tested for near- and far-field shielding effectiveness (SE). Far-field SE was tested using a modified standard measurement technique to provide results comparable with the company-provided data. Further, housings of different thermoplastic materials were constructed and equipped with an electromagnetic interference (EMI) source to model a realistic near-field SE situation. The SE data up to 1 GHz is presented. Conductive thermoplastic materials with fillings of stainless steel fibers and nickel-coated carbon fibers were the two materials that offer the best far-field shielding performance. For the near-field shielding, two materials with filling of stainless steel fibers were the best performing ones. A thermoplastic with polycarbonate (PC) base and stainless steel content of 1.5 vol% showed the best combined far- and near-field shielding results     

Wafer Direct Bonding: From Advanced Substrate Engineering to Future Applications in Micro/Nanoelectronics

Wafer direct bonding refers to the process of adhesion of two flat mirror-polished wafers without using any intermediate gluing layers in ambient air or vacuum at room temperature. The adhesion of the two wafers occurs due to attractive long range van der Waals or hydrogen bonding forces. At room temperature the bonding energy of the interface is low and higher temperature annealing of the bonded wafer pairs has to be carried out to enhance the bonding energy. In this paper, we describe the prerequisites for the wafer-bonding process to occur and the methods to prepare the suitable surfaces for wafer bonding. The characterization techniques to assess the quality of the bonded interfaces and to measure the bonding energy are presented. Next, the applications of wafer direct bonding in the fabrication of novel engineered substrates such as "silicon-on-insulator" and other "on-insulator" substrates are detailed. These novel substrates, often called hybrid substrates, are fabricated using wafer bonding and layer splitting via a high dose hydrogen/helium implantation and subsequent annealing. The specifics of this process, also known as the smart-cut process, are introduced. Finally, the role of wafer bonding in future nanotechnology applications such as nanotransistor fabrication, three-dimensional integration for high-performance micro/nanoelectronics, nanotemplates based on twist bonding, and nano-electro-mechanical systems is discussed     

A 3-GHz 70-mb SRAM in 65-nm CMOS technology with integrated column-based dynamic power supply

Column-based dynamic power supply has been integrated into a high-frequency 70-Mb SRAM design that is fabricated on a high-performance 65-nm CMOS technology. The fully synchronized design achieves a 3-GHz operating frequency at 1.1-V power supply. The power supply at SRAM cell array is dynamically switched between two different voltage levels during READ and WRITE operations. Silicon measurement has proven this method to be effective in achieving both good cell READ and WRITE margins, while lowering the overall SRAM leakage power consumption.     

Millimeter-wave design considerations for power amplifiers in an SiGe process technology

This paper describes a number of significant modeling considerations for SiGe heterojunction bipolar transistor power amplifiers operating at millimeter-wave frequencies. Small- and large-signal model-to-hardware correlation is presented for single transistor amplifiers, as well as for a combined dual-stage amplifier up to 65 GHz. The relevant parasitic effects are described along with the proposed modeling approach for each of them. The limits of the standard Vertical Bipolar Inter-Company device model at high-injection and their effect on the prediction of the achievable large-signal compression and power-added efficiency are also discussed.     

Determination of the complex permittivity of packaging materials at millimeter-wave frequencies

The focus of this paper is the determination of the complex permittivity of chip packaging materials at millimeter-wave frequencies. After a broad overview of existing measurement techniques, three methods will be presented that have been established for the dielectric property determination of substrate, as well as mold materials (encapsulants, under-fill, etc.) in the millimeter-wave frequency range. First, the open resonator used here will be briefly described. It allows accurate determination of the dielectric constant and loss of thin sheet substrate materials from below 20 GHz to above 100 GHz. Second, a filled waveguide method is explained in detail. The setup used here can determine the complex dielectric properties of mold materials from 70 to 100 GHz. Third, the method based on covered transmission lines will be described in detail. The used lines allow measurements from below 40 GHz to approximately 90 GHz. Verification of all three methods will be provided by inter-comparison and comparison to values from the literature. Additionally, results for several typical substrate and mold materials that are available for millimeter-wave packaging will be shown and discussed.