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Both intrinsic and extrinsic semiconductors are discussed in terms of their band structure. The acceptor and donor energy levels are introduced. Scattering is discussed, from which the conductivity of semiconductors is derived. Some mathematical relations between electron and hole densities are derived. The mobilities of III–V and II–VI compounds and their dependence on impurity concentrations are discussed. Band structures of real and idealized semiconductors are contrasted. Measurements of semiconductor properties are reviewed. Various possibilities for optical excitation of electrons are discussed. The technology of crystal growth and purification are reviewed, in particular, molecular beam epitaxy and metal-organic chemical vapour deposition.

A classic text in the field providing a readable and accessible guide for students of electrical and electronic engineering. Fundamentals of electric properties of materials are illustrated and put into context with contemporary applications in engineering. Mathematical content is kept to a minimum allowing the reader to focus on the subject. The starting point is the behaviour of the electron, which is explored both in the classical and in the quantum-mechanical context. Then comes the study of bonds, the free electron model, band structure, and the theory of semiconductors, followed by a chapter on semiconductor devices. Further chapters are concerned with the fundamentals of dielectrics, magnetic materials, lasers, optoelectronics, and superconductivity. The last chapter is on metamaterials, which has been a quite popular subject in the past decade. The book includes problems, the worked solutions are available in a separate publication: Solutions manual for electrical properties of materials. There is an appendix giving a list of Nobel Prize winners whose work was crucial for describing the electric properties of materials, and there are further appendices giving descriptions of phenomena which did not fit easily within the main text. In particular there is a quite detailed appendix that summarizes the properties of memory elements. The book is ideal for undergraduates, and is also an invaluable reference for graduate students and others wishing to explore this rapidly changing field.

Two-state and three-state systems are introduced. The properties of gaseous, solid state, and dye lasers are discussed and particular attention is devoted to semiconductor lasers. Reducing the dimensions leading to wells, wires, and dots is shown to have advantages. Quantum cascade lasers working in the THz region are discussed. The phenomena of Q switching, cavity dumping, and mode locking are explained. Parametric oscillators and optical fibre amplifiers are discussed. Masers are briefly mentioned. Laser noise is discussed. Awide variety of applications are mentioned. The curious phenomenon of laser cooling is explained. The basic principles of holographic recording and display are described.

The properties of light detectors and light emitting diodes (LEDs) are discussed. Electro-optic, photorefractive, and nonlinear materials are introduced. The phenomenon of phase conjugation is explained. Interaction between acoustic and light waves is shown to be possible. The significance of integrated optics is discussed. Bistability due to the action of nonlinear Fabry–Perot cavities is explained. Optical switching is shown to be an application of micro-electro-mechanical effects. The complicated phenomenon electro-absorption in quantum well structures and its applications are discussed.

Macroscopic and microscopic theories of magnetic polarization are discussed. The origin of domains, domain walls, and of the hysteresis curve and the contrast between soft and hard magnetic materials are explained. The more important elements of the quantum theory of magnetism are discussed. The principles of the alignments in antiferromagnetic and ferromagnetic materials are explained. Magnetic resonance phenomena are discussed. Magnetoresistance and spintronics and their device prospects are also discussed at some length.

Mechanical properties of bonds are discussed, with the aid of a simple phenomenological model in which the variation of energy as a function of distance between the elements is described in terms of polynomials. The properties of various kinds of bonds (ionic bond, metallic bond, covalent bond, van der Waals bond) are explained with the aid of simple models. Carbon is discussed with two examples: bonds between 60 atoms that lead to the formation of a three-dimensional molecule known as Buckminsterfullerene, and the alternative sheet-shaped configuration known as graphene, that has recently become the centre of interest. A general theory for finding the energy levels is introduced, relying on Feynman’s coupled wave equations. There is a brief reference to nuclear forces, followed by a discussion of the hydrogen molecule. The relationship between coupling and the splitting of the energy levels is discussed with an analogy to coupled resonant circuits.

Discusses with some rigour the properties of electrons, based on the Schrodinger equation. Introduces the concepts of wave function, quantum-mechanical operators, and wave packets. Examples cover the electron meeting an infinitely long potential barrier and the passage of electrons through a finite barrier (which leads to the phenomenon of tunnelling).The electron in a potential well is also discussed, solving the problem both for a finite and for an infinite well, and finding the permissible energy levels. The chapter is concluded with the philosophical implications that arise from the quantum-mechanical approach. Two limericks relevant to the subject are quoted.

The virtues of the profession of engineering are extolled. The views of one of the greatest electrical engineers (Rudolf Kompfner) of the last century are quoted as follows: “The feeling one experiences when he obtains a new important insight when a crucial experiment works, when an idea begins to grow and bear fruit, these mental states are indescribably beautiful and exciting. Nomaterial reward can produce effects even distantly approaching them. Yet another benefit is that an inventor can never be bored. There is no time when I cannot think of a variety of problems. All waiting to be speculated about, perhaps tackled, perhaps solved. All one has to do is to ask the questions, why? How? And not be content with the easy, the superficial answer.”

The macroscopic and microscopic approaches to determining polarization are explained. The types of polarization, frequency response, and anomalous dispersion are discussed. The Debye equation for orientational polarization is derived. The concept of effective field is introduced. The dispersion equations for acoustic waves and for optical phonons are derived. The properties of piezoelectricity, pyroelectricity, and ferroelectricity are discussed. The attenuation of optical fibres, the operation of a photocopier, and the ability of liquid crystals to rotate polarization are also discussed.

All 32 survivors with transposition of the great arteries, born in 1964-83 and operated on at our institution using atrial redirection, were evaluated by cardiac catheterization, echocardiography and Holter monitoring. There were 17 Mustard patients, age 17.1 years (±3.5, 12.0-22.0) and 15 Senning patients, age 9.4 years (±1.6, 7.2-12.1). All but one had simple transposition. Six had caval obstruction, one had pulmonary venous obstruction, three had large atrial shunts, four had considerable pulmonary hypertension, seven had mild ventricular outflow tract obstruction, four had significant tricuspid regurgitation, 11 had systemic ventricle dysfunction (one severe), 14 had sinus node dysfunction (three symptomatic) and two had atrioventricular block (one with pacemaker). Eight Mustard patients (47%) and one Senning patient (7%) had symptomatic cardiac sequelae, and only one patient (Senning) was free from sequelae, illustrating that these patient groups will need continuing medical attention.

Waves in periodic media, whose propagation is governed by nearest neighbour interaction, are investigated. The reflection and transmission coefficients are derived for a plane wave incident from medium 1 upon medium 2, without invoking common approximations. The derivation is valid for a class of waves including magneto- and electro-inductive waves, waves on short loaded dipoles, nanoparticles, coupled waveguides and acoustic waves in monatomic media. For this last case hitherto unknown microscopic reflection and transmission coefficients are derived and shown to reduce in the continuous limit to the well-known expressions in terms of acoustic impedances.

Previous studies of magnetoinductive waves in homogeneous media with resonant elements consisting of capacitively loaded metallic loops are extended to the case when a single wave from one medium is incident upon another one. The relationship between the input and output angles and the reflection and transmission coefficients are determined with the aid of the dispersion equation for different scenarios. An expression is obtained for the power density vector, and it is shown that its component perpendicular to the boundary is conserved across the boundary. Using different configurations of the elements it is shown that both positive and negative refraction may occur.

The response of a metamaterial, consisting of a 3D lattice of lossy capacitively loaded metallic loops is studied theoretically when it is inserted into a homogeneous harmonically varying magnetic field. The current distribution is found by taking into account the magnetic coupling between any pair of loops in the approximation of no retardation. It is shown that in a frequency range above its resonant frequency the metamaterial behaves as a diamagnet expelling the applied magnetic field. As the resonant frequency is approached the magnetic field is shown to be expelled not only from the volume of the metamaterial but from a larger zone which in the vicinity of the resonant frequency takes the form of a sphere. In the lossless case the radius of this exclusion sphere tends to infinity. In the presence of losses the maximum radius is limited by the quality factor of the individual elements. The response of a single element is shown to be analogous to that of a sphere of magnetic material, an analogy that leads to an alternative definition of effective permeability.

A differential equation and boundary conditions are derived for the amplitude of the first harmonic of the space-charge field in the case of a lossy thin photorefractive film with anisotropic conductivity that is illuminated by a moving interference pattern. It is shown that for certain values of the anisotropy parameter, detuning, and film thickness, a new resonance phenomenon may occur. This resonance is distinct from and additional to the one that relies on the agreement between the speed of the interference pattern and that of the space charge wave, and has been known for a long time.

UNLABELLED A 2-y-old boy with scimitar syndrome underwent surgery involving the redirection of partial anomalous pulmonary venous return to the left atrium. Heart catheterization after the operation did not reveal any significant intra-cardiac shunts. An exercise test performed at the age of 10 y revealed a reduction in working capacity. At the age of 12 y, the patient became unconscious and experienced seizures during heavy physical exercise. EEG and Holter ECG examinations were normal. In a second exercise test, a fall in transcutaneous PO2 was demonstrated at the start of the test. A new heart catheterization revealed communication between the inferior vena cava and the left atrium owing to a misplaced patch. No right-to-left shunt was found at rest, probably as a result of drainage of the inferior vena cava to the superior vena cava by the azygous vein. An exercise test after re-operation revealed normal conditions. CONCLUSION Haemodynamic studies during heart catheterization in children are usually performed at rest. This could result in exercise-induced right-to-left-shunts being overlooked. The use of PtcO2 monitoring during exercise tests is a non-invasive means of exposing these shunts.

We show that reconstructing a hologram by its object beam leads to spatial filtering, namely, to the suppression of spatial frequency components that are perpendicular to the plane of the recording beams. We conduct experiments by rotating the transparencies of Ronchi gratings and crossed gratings and measuring the corresponding diffraction efficiencies. Good agreement is found with a theory based on image reconstruction with a beam that does not quite satisfy the Bragg condition.

A broadband resonant transducer capable of low-loss coupling between magneto-inductive (MI) waveguides and a real impedance is introduced. The transducer is an L–C circuit resonating at the resonant frequency of the elements forming the guide. However, the values of the components in the transducer are different, and chosen to obtain two separate nulls in reflection so that low reflection is obtained over a wide spectral range. The transducer can be incorporated into the MI waveguide itself, allowing a connection between a MI cable and a conventional system to be made as a simple splice. The design is confirmed using 2 m length of low-loss thin-film MI cables formed using copper-clad polyimide and operating near 100 MHz frequency.

The flow of spatially periodic current in a photorefractive film is investigated under the conditions when two coherent plane waves are incident and an electric field is applied. It is shown that in contrast to the usually accepted physical picture the major part of the current does not flow in a simple manner from one boundary to the other boundary. Two examples are given: (i) transients in the perpendicular configuration (grating vector perpendicular to the direction of the applied field) with vertical diffusion neglected and (ii) steady state in the parallel configuration (grating vector parallel with the applied electric field) with vertical diffusion included. The flow of current is plotted with the aid of vector diagrams. It is clearly shown that during transients current may flow from one point on the boundary to another point on the same boundary, and that for the parallel configuration circular currents may flow in the steady state.

The linearized Ericksen-Leslie differential equations, which couple fluid motion and director reorientation to each other, are reduced to a set of time varying differential equations for two pulsed optical waves incident at an angle upon a homeotropically orientated liquid-crystal cell. The differential equations are solved by a numerical method. The fluid velocity and the director angle are plotted as a function of space and time. It is shown that the reaction of fluid motion upon director reorientation is small.

Theoretical investigations, relying mainly on numerical solutions of the non-linear differential equations of the reorientation angle, are conducted for a wide range of parameters and for a number of physical configurations which include self-diffraction and fast transients. The experiments are performed using homeotropically aligned 5CD liquid crystalscells. In particular, the temporal evolution of a ring structure in the far field pattern and response to short pulses are investigated involving time scales from nanosecond to tens of seconds regions. Comparisons between experimental results and theoretical predictions show that excellent match can be achieved for any one experiment by the choice of parameters like optical anisotropy, elastic constant and viscosity, but when parameter values derived from different experiments are compared, these parameters turn out to depend on the experimental conditions.

The three-wave interaction between two oppositely propagating acoustic waves and a wave of bound space charge is studied in a uniformly illuminated piezoelectric and photorefractive crystal. A nonlinear partial differential equation describing the space charge field is derived taking into account the piezoelectric effect. The steady state solution is found in the approximation of undepleted acoustic waves. It is shown that the efficient resonant excitation of the space charge wave is possible if the detuning between the acoustic waves is equal to its eigen-frequency. The acoustic nonlinearity caused by the interaction with the space charge wave is compared with the nonlinearity caused by the ordinary acousto-electronic interaction. Amplitudes of optical gratings produced by the space charge wave and the acoustic wave are also compared.

A photorefractive oscillator. mutually pumped by three wavelengths is presented in various configurations and competition effects demonstrated. The theoretical model used to simulate the behaviour of the oscillation beams is in good agreement with experimental data.

The excitation of a space charge wave in a uniformly illuminated photorefractive crystal by an applied ac voltage is studied theoretically. A spatial differential equation for the ac component of the space charge field is derived and boundary conditions applicable both to Ohmic and rectifying junctions are obtained leading to an analytical solution for the space charge wave amplitude. It is shown that the low frequency space charge wave associated with the recharge of impurities can be efficiently excited with an amplitude approximately equal to the applied ac field. For the parameters of a BSO crystal, the space charge wave region declines within a few grating spacings near the cathode. The possibility of experimental observation of the effect is discussed.

An energy balance equation is derived with the aid of a partial differential equation describing the space‐charge field in photorefractive materials. Expressions are found for power flux, losses, and the power absorbed from an external source both for the low‐ and high‐frequency branches of space‐charge waves. The efficiency of energy conversion from the external source into the space‐charge wave is calculated and compared for two different mechanisms of optical excitation: (i) by a moving interference pattern and (ii) by a combination of a stationary interference pattern and an external ac field.

It is shown theoretically that the space charge field generated by two‐wave mixing in a photorefractive crystal may have a resonant response when a dc field and a sinusoidal ac field are simultaneously applied. Resonance occurs when the frequency of the ac field is equal to the eigenfrequency of the space charge wave determined by the dc voltage. Analytical expressions are derived for the magnitude of the space charge wave and the optimum ratio of the ac to dc field is determined. The enhancement of the space charge field is shown to be considerably higher than that obtained by a nonresonant method utilizing a sinusoidal ac field alone. Under optimum conditions the maximum space charge field available is equal to mEq/2√2, where m is the modulation of the interference pattern and Eq is the saturation field.

Since the first observation of the spatial subharmonics in photorefractive BSO crystal by Mallick et al. 1988, the possible physical mechanism based on the Kukhtarev's materials equations has been intensively investigated. However, most of the work in this field has been concentrated on obtaining the instability condition for the existence of the subharmonic resonances. In this paper we attempt to calculate K/2 spatial subharmonic resonances varying the detuning frequencies for several external electric fields and compare the theoretical results with experimental data. A simple theory based on a differential equation which is derived from the materials equations for the space charge field and the coupled mode analysis of the wave equation is developed to describe the subharmonic resonances. The mechanism which is responsible for the subharmonic resonance is assumed to be spontaneous generation caused by the inherent nonlinearity of the photorefractive effect. >

A 2-y-old boy with scimitar syndrome underwent surgery involving the redirection of partial anomalous pulmonary venous return to the left atrium. Heart catheterization after the operation did not reveal any significant intra-cardiac shunts. An exercise test performed at the age of 10 y revealed a reduction in working capacity. At the age of 12 y, the patient became unconscious and experienced seizures during heavy physical exercise. EEG and Holter ECG examinations were normal. In a second exercise test, a fall in transcutaneous PO2 was demonstrated at the start of the test. A new heart catheterization revealed communication between the inferior vena cava and the left atrium owing to a misplaced patch. No right-to-left shunt was found at rest, probably as a result of drainage of the inferior vena cava to the superior vena cava by the azygous vein. An exercise test after re-operation revealed normal conditions.Haemodynamic studies during heart catheterization in children are usually performed at rest. This could result in exercise-induced right-to-left-shunts being overlooked. The use of PtcO2 monitoring during exercise tests is a non-invasive means of exposing these shunts.

Critical aortic stenosis (CAOS) is not compatible with life when the ductus arteriosus closes. We have treated 11 consecutive cases with isolated CAOS. Symptom presentation was in the early neonatal period and diagnosis was made noninvasively at a mean age of 4 days. All were operated on with transventricular dilation (TVD) at a mean age of 4.7 days. There was no early mortality. There were two late deaths due to fibroelastosis. Both had the smallest aortic anulus diameter (5 mm). Two other patients had aortic root replacement, one at the age of 6.5 weeks due to intractable heart failure, and the other at the age of 3 months due to increasing gradient. In these two cases elective surgery was made possible by a sucessful TVD in the early neonatal period. TVD in this material was not associated with any early mortality, which makes this procedure a good alternative in the treatment of CAOS.

To describe the radiographic appearance of the Gianturco and the Cook detachable coils and present the clinical results in patients who underwent transcatheter closure of patent ductus arteriosus.Between January 1994 and June 1997, eighty-two patients underwent closure of patent ductus arteriosus (PDA) using either Gianturco or Cook detachable coils. The chest x-ray and echocardiography of all patients were reviewed and the following parameters were evaluated: 1) the size of the heart (cardiothoracic ratio), 2) the position and the type of the coils in the postero-anterior and the lateral projection, 3) the number of coils used, 4) the existence of residual ductal flow, 5) Doppler velocity in the left pulmonary artery.Complete occlusion was achieved in 94%, and cardio-thoracic ratio regressed from 0.57 to 0.53 (p0.01), after a mean follow-up of 1.2 years. The identification of the different coils on the chest radiograph was successful in only 47% of cases, difficulties arising especially, when multiple coils were used. In 55 patients (67%) the coil position was judged to be optimal, in 27 patients (33%) suboptimal. The latter correlates with the presence of residual shunt. Multiple coils correlated more with a left pulmonary artery flow velocity exceeding 1.5 m/s.Coil-occlusion of patent ductus arteriosus is effective and leads to reduced cardio-thoracic ratio. Radiographic coil identification is possible but may be difficult if multiple coils are deployed. Suboptimal coil position led more often to residual PDA shunt. Multiple coils are more commonly associated with increased LPA velocities, but hemodynamic significant obstruction to flow is rare.

All 32 survivors with transposition of the great arteries, born in 1964-83 and operated on at our institution using atrial redirection, were evaluated by cardiac catheterization, echocardiography and Holter monitoring. There were 17 Mustard patients, age 17.1 years (+/-3.5, 12.0-22.0) and 15 Senning patients, age 9.4 years (+/-1.6, 7.2-12.1). All but one had simple transposition. Six had caval obstruction, one had pulmonary venous obstruction, three had large atrial shunts, four had considerable pulmonary hypertension, seven had mild ventricular outflow tract obstruction, four had significant tricuspid regurgitation, 11 had systemic ventricle dysfunction (one severe), 14 had sinus node dysfunction (three symptomatic) and two had atrioventricular block (one with pacemaker). Eight Mustard patients (47%) and one Senning patient (7%) had symptomatic cardiac sequelae, and only one patient (Senning) was free from sequelae, illustrating that these patient groups will need continuing medical attention.

A method for finding the effective permeability of metamaterials is presented, based on the interaction between electromagnetic and magnetoinductive waves. Assuming a coupled circuit model for the interaction, a dispersion equation is derived that exhibits two types of bandgaps, one leading to complex solutions and the other to purely evanescent waves. Although losses are disregarded, the effective permeability (in contrast to established theories) is shown to have an imaginary part in part of the stop band, while its real part remains finite in both the pass band and the stop band.