There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

I have developed "tennis elbow" from lugging this book around the past four weeks, but it is worth the pain, the effort, and the aspirin. It is also worth the (relatively speaking) bargain price. Including appendixes, this book contains 894 pages of text. The entire panorama of the neural sciences is surveyed and examined, and it is comprehensive in its scope, from genomes to social behaviors. The editors explicitly state that the book is designed as "an introductory text for students of biology, behavior, and medicine," but it is hard to imagine any audience, interested in any fragment of neuroscience at any level of sophistication, that would not enjoy this book. The editors have done a masterful job of weaving together the biologic, the behavioral, and the clinical sciences into a single tapestry in which everyone from the molecular biologist to the practicing psychiatrist can find and appreciate his or

Principles of Neural Science

This article reviews the current status of lattice-dynamical calculations in crystals, using density-functional perturbation theory, with emphasis on the plane-wave pseudopotential method. Several specialized topics are treated, including the implementation for metals, the calculation of the response to macroscopic electric fields and their relevance to long-wavelength vibrations in polar materials, the response to strain deformations, and higher-order responses. The success of this methodology is demonstrated with a number of applications existing in the literature.

/pdf/phonons-and-related-crystal-properties-from-density-3mdybdn8w1.pdf

Phonons and related crystal properties from density-functional perturbation theory

We present a comprehensive, up-to-date compilation of band parameters for the technologically important III–V zinc blende and wurtzite compound semiconductors: GaAs, GaSb, GaP, GaN, AlAs, AlSb, AlP, AlN, InAs, InSb, InP, and InN, along with their ternary and quaternary alloys. Based on a review of the existing literature, complete and consistent parameter sets are given for all materials. Emphasizing the quantities required for band structure calculations, we tabulate the direct and indirect energy gaps, spin-orbit, and crystal-field splittings, alloy bowing parameters, effective masses for electrons, heavy, light, and split-off holes, Luttinger parameters, interband momentum matrix elements, and deformation potentials, including temperature and alloy-composition dependences where available. Heterostructure band offsets are also given, on an absolute scale that allows any material to be aligned relative to any other.

Band parameters for III–V compound semiconductors and their alloys

The need to develop inexpensive renewable energy sources stimulates scientific research for efficient, low-cost photovoltaic devices.1 The organic, polymer-based photovoltaic elements have introduced at least the potential of obtaining cheap and easy methods to produce energy from light.2 The possibility of chemically manipulating the material properties of polymers (plastics) combined with a variety of easy and cheap processing techniques has made polymer-based materials present in almost every aspect of modern society.3 Organic semiconductors have several advantages: (a) lowcost synthesis, and (b) easy manufacture of thin film devices by vacuum evaporation/sublimation or solution cast or printing technologies. Furthermore, organic semiconductor thin films may show high absorption coefficients4 exceeding 105 cm-1, which makes them good chromophores for optoelectronic applications. The electronic band gap of organic semiconductors can be engineered by chemical synthesis for simple color changing of light emitting diodes (LEDs).5 Charge carrier mobilities as high as 10 cm2/V‚s6 made them competitive with amorphous silicon.7 This review is organized as follows. In the first part, we will give a general introduction to the materials, production techniques, working principles, critical parameters, and stability of the organic solar cells. In the second part, we will focus on conjugated polymer/fullerene bulk heterojunction solar cells, mainly on polyphenylenevinylene (PPV) derivatives/(1-(3-methoxycarbonyl) propyl-1-phenyl[6,6]C61) (PCBM) fullerene derivatives and poly(3-hexylthiophene) (P3HT)/PCBM systems. In the third part, we will discuss the alternative approaches such as polymer/polymer solar cells and organic/inorganic hybrid solar cells. In the fourth part, we will suggest possible routes for further improvements and finish with some conclusions. The different papers mentioned in the text have been chosen for didactical purposes and cannot reflect the chronology of the research field nor have a claim of completeness. The further interested reader is referred to the vast amount of quality papers published in this field during the past decade.

Conjugated polymer-based organic solar cells

This paper presents a 600 V, 55 mS GaN cascode with slew rate control. The time constants of cascodes which determine the switching speed are analyzed, discussed and verified by time domain simulations. Clamped inductive switching measurements of commercial and a custom-built GaN cascodes prove the applicability of the switching speed control mechanisms with additional passive components. The gathered experiences are applied to a custom-built modular cascode, which shows simple switching speed controllability by utilizing a standard gate drive.

Slew rate control of a 600 V 55 mΩ GaN cascode

Key components and architecture options are being actively investigated to realize next generation transport technology in optical networks. Serial transmission systems using a single wavelength have, so far, provided cost effective solutions and therefore remain desirable. For 100 Gbit/s Ethernet, this option will, however, depend on the availability of the electronic and optical components. Due to its high speed and high breakdown voltage, the InP double-heterojunction bipolar transistor (DHBT) technology is particularly suited for signal processing and high-speed communication systems. This contribution describes our InP DHBT based integrated circuit (IC) technology developed for 100 Gbit/s class mixed-signal ICs. Using this technology, we fabricated and succeeded in 112 Gbit/s testing of key electronic components, including a multiplexer (MUX), a distributed amplifier, and an integrated clock and data recovery (CDR)/1:2 demultiplexer (DEMUX), with very clear eye waveforms. These high-speed building block ICs are described and the main results are presented.

Ultra-High-Speed Transmitter and Receiver ICs for 100 Gbit/s Ethernet Using InP DHBTs

We carried out reflectance and spectroscopic ellipsometry measurements of high-purity c -plane epitaxial films of wurtzite GaN in a temperature range 5-840 K. Analysis of the data reveals three main contributions to the dielectric function related to optical transitions involving discrete exciton states, excitonic continuum and exciton-phonon complexes, respectively. The observed contributing mechanisms show different temperature dependence. This behavior is related to specific interactions between optical excitations and thermal LO phonons. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Excitons and exciton‐phonon coupling in the optical response of GaN

Two monolithic microwave integrated circuit low noise amplifiers for 67-116 GHz have been developed using the 50 nm metamorphic high electron mobility transistor technology of Fraunhofer IAF. Both amplifiers have been measured on-wafer at room temperature and one of them additionally in a waveguide module at an ambient temperature of 18 K. The average gain and noise temperature in the band 75-110 GHz are 23 dB and 69 K, respectively, in the latter case.

Cryogenic low noise amplifier development for 67–116 GHz

This paper reports a scalable small-signal modeling approach for III-V high electron mobility transistors. The model utilizes a distributed six port description of the three transistor electrodes which improves the model validity up to very long finger lengths. The planar transistor structure is modeled directly as given by its layout, which enables realistic modeling of coupling effects rather than using an abstract shell-description. A wide range of bias points is covered using third order Taylor expansions to calculate the bias dependent parameters. The modeling approach is verified at the example of an InGaAs metamorphic high electron mobility transistor technology with 50 nm gate length.

Oliver Ambacher

Papers

Slew rate control of a 600 V 55 mΩ GaN cascode

Ultra-High-Speed Transmitter and Receiver ICs for 100 Gbit/s Ethernet Using InP DHBTs

Excitons and exciton‐phonon coupling in the optical response of GaN

Cryogenic low noise amplifier development for 67–116 GHz

Highly Scalable Distributed High Electron Mobility Transistor Model