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

High-electron-mobility transistors (HEMTs) based on AlGaN/GaN heterostructures were successfully tested as chemically sensing devices. Exposing the unprotected polar GaN surface in the gate area of a HEMT to liquids of different polarity, milliampere changes in the source-drain current could be detected. These sensing effects are likely to arise from chemical interactions with a sheet of ionic charge on the free GaN surface which compensates the electronic charge of a two-dimensional electron gas at a subsurface AlGaN/GaN interface.

High-Electron-Mobility AlGaN/GaN Transistors (HEMTs) for Fluid Monitoring Applications

In Si doped AlN, a large persistent photoconductivity is found for temperatures below 60 K after exposure to light with photon energies above 1.5 eV. Simultaneously, a persistent electron spin resonance signal is observed with an isotropic g factor of 1.9885 due to an effective mass donor state, while no spin resonance signal is detectable after cooling the sample in the dark. Both observations show that Si undergoes a $\mathrm{DX}$-like metastability in this material. Based on the experimental findings, a detailed configuration diagram is proposed.

DX -behavior of Si in AlN

https://www.phas.ubc.ca/~beaudoin/PDS%20Papers/PDS%20papers%20from%20other%20authors/SSC97_365%20PDS%20subEg%20GaN.pdf

Sub-bandgap absorption of gallium nitride determined by Photothermal Deflection Spectroscopy

We report on the phase stabilization of rhombohedral (rh-) In2O3 films on sapphire substrate deposited by metal organic chemical vapor deposition With the help of a high-temperature nucleation layer and evolutionary structural selection of rhombohedral phase during the growth process, stable epitaxial growth of single crystalline rh-In2O3 is achieved The mechanism of phase selective epitaxial growth is studied by means of high-resolution X-ray diffraction and transmission electron microscopy measurements Furthermore, Raman spectroscopy measurements are carried out to investigate the phonon properties of rh-In2O3 Raman-active phonon modes of rh-In2O3 are first identified

Phase Stabilization and Phonon Properties of Single Crystalline Rhombohedral Indium Oxide

An aluminum nitride/diamond p–n heterojunction has been realized by plasma-induced molecular-beam epitaxy growth of AlN on (100) diamond. The epitaxial nature of this heterojunction has been confirmed by high-resolution x-ray diffraction. The silicon-doped AlN film (n-type) on the natural boron-doped (p-type) diamond substrate formed a heterobipolar diode with good rectifying properties and surprisingly efficient light emission in the spectral range from 2.7 to 4.8 eV under forward bias. Results concerning the structural, electrical, and optical characterization of the AlN/diamond heterojunction are reported in this letter.

Oliver Ambacher

Papers

High-Electron-Mobility AlGaN/GaN Transistors (HEMTs) for Fluid Monitoring Applications

DX -behavior of Si in AlN

Sub-bandgap absorption of gallium nitride determined by Photothermal Deflection Spectroscopy

Phase Stabilization and Phonon Properties of Single Crystalline Rhombohedral Indium Oxide

AlN/diamond heterojunction diodes