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Hot carrier solar cells hold the promise of efficiency significantly greater than that predicted by the Shockley–Queisser limit. Consequently, there has been considerable effort to create cells that achieve this goal, but so far, this has not been realized. There are many reasons for this. Here, the principles of the concept will be discussed along with some myths that hinder the future development of such devices. Also, a new approach to the hot carrier solar cell is described along with some recent experimental results that support such an approach. [ABSTRACT FROM AUTHOR]

Dilute-N GaPAsN alloys have great potential for optoelectronics lattice-matched to Si. However, there is a lack of systematic calculation of the optical response of these alloys. The present paper uses the s p 3 d 5 s ∗ s N tight-binding model to calculate the fullband electronic structure of dilute-N GaPAsN and then calculate the optical response functions considering direct transitions within the electric dipole approximation. Good agreement is obtained for the dielectric function in comparison to available optical data for dilute nitrides. To achieve this, the s p 3 d 5 s ∗ parameters for GaP and GaAs are optimized for their optical properties in comparison to published data, which are then used as the basis for the s p 3 d 5 s ∗ s N parameters for dilute-N GaPN and GaAsN. The calculated absorption between the valence band and the newly formed lowest conduction band of the dilute nitrides increases as the N fraction increases, in agreement with experiments, mainly due to the net increase in their coupling in the entire Brillouin zone, supported by the calculated momentum matrix element in the present work. [ABSTRACT FROM AUTHOR]

We investigate the effects of electron and acoustic phonon confinements on the low-field electron mobility of thin, gated, square silicon nanowires (SiNWs), surrounded by SiO2. We employ a self-consistent Poisson–Schrödinger–Monte Carlo solver that accounts for scattering due to acoustic phonons (confined and bulk), intervalley phonons, and the Si/SiO2 surface roughness. The wires considered have cross sections between 3×3 and 8×8 nm2. For larger wires, the dependence of the mobility on the transverse field from the gate is pronounced, as expected. At low transverse fields, where phonon scattering dominates, scattering from confined acoustic phonons results in about a 10% decrease in the mobility with respect to the bulk phonon approximation. As the wire cross section decreases, the electron mobility drops because the detrimental increase in both electron-acoustic phonon and electron-surface roughness scattering rates overshadows the beneficial volume inversion and subband modulation. For wires thinner than 5×5 nm2, surface roughness scattering dominates regardless of the transverse field applied and leads to a monotonic decrease in the electron mobility with decreasing SiNW cross section. [ABSTRACT FROM AUTHOR]

We characterize the linear and nonlinear electron transport in quantum point contacts (QPCs) realized by a hybrid combination of etching and gating. We demonstrate that the strong electron confinement generated through this hybrid QPC process results in quantized subbands with a large energy separation, leading to the observation of robust one-dimensional quantum-transport effects. Measurements of the nonlinear differential conductance reveal an unexpected bunching of curves at 0.20-0.25×2e2/h, rather than at the expected value of 0.5×2e2/h. Application of a simple analytical model indicates that this bunching is associated with the highly asymmetric manner in which the source-drain voltage is dropped across the QPC near pinch-off and under nonequilibrium conditions. [ABSTRACT FROM AUTHOR]

Emphasizes that the normal operation of evaporated ZnS:Mn alternating-current thin-film electroluminescent devices involves electron-hole pair generation by band-to-band impact ionization. Expression for the impact ionization coefficient; Evidence for band-to-band impact ionization; Information on the Monte Carlo high-field transport simulation.

Presents a study which fabricated quantum wave guide structures with double-bend discontinuities in modulation-doped AlGaAs/gallium arsenide heterojunctions using a split-gate technique. Wave guide effects in quantum wires with double-bend discontinuities; Typical quantum wave guide structure; Bend resonances in quantum wave guides with different dimensions.

Presents a study that examined the transport properties of the two-dimensional electron gas in selectively doped Al[suby]Ga[sub1-y]As/In [subx]Ga[sub1-x]As/GaAs pseudomorphic structures grown by molecular beam epitaxy. Experimental details; Results of the study; Conclusion.

Presents a Monte Carlo simulation of electron transport in alternating-current thin film electroluminescent (ACTFEL) devices. Approaches used to describe ACTFEL electronic transport in the high-field regime; Description of the Monte Carlo simulation method; Scattering rates for various scattering mechanisms as a function of energy for electron transport.

Presents the results of an investigation of neutron irradiation effects on the collector-emitter offset voltage of InP/InGaAs single heterojunction bipolar transistors. Increase in the offset voltage of the devices; Analysis of the forward and inverse Gummel plots.

The low-field electron mobility in rectangular silicon nanowire (SiNW) transistors was computed using a self-consistent Poisson-Schroumldinger-Monte Carlo solver. The behavior of the phonon-limited and surface-roughness-limited components of the mobility was investigated by decreasing the wire width from 30 to 8 nm, the width range capturing a crossover between two-dimensional and one-dimensional electron transport. The phonon-limited mobility, which characterizes transport at low and moderate transverse fields, is found to decrease with decreasing wire width due to an increase in the electron-phonon wavefunction overlap. In contrast, the mobility at very high transverse fields, which is limited by surface roughness scattering, increases with decreasing wire width due to volume inversion. The importance of acoustic phonon confinement is also discussed briefly [ABSTRACT FROM PUBLISHER]

In this paper, the authors discuss the anticipated curriculum of electrical and computer engineering (ECE) programs in the year 2013 and beyond for a prototypical metropolitan public research university. Assumptions are made regarding the evolution of the relevant technology addressed by the curriculum, the nature of metropolitan public universities in the next decade, and the nature of the learning environment, technology, and educational focus based on present trends. A 128-credit-hour curriculum is proposed that addresses these challenges. [ABSTRACT FROM AUTHOR]

Impact ionization plays a crucial role for electron transport in wide-bandgap semiconductors at high electric fields. Therefore, a realistic band structure has to be used in calculations of the microscopic scattering rate, as well as high field quantum corrections such as the intercollisional field effect. Here we consider both, and evaluate the impact ionization rate for wide-bandgap materials such as ZnS. A pronounced softening of the impact ionization threshold is obtained, as found earlier for materials like Si and GaAs. This field dependent impact ionization rate is included within a full-band ensemble Monte Carlo simulation of high field transport in ZnS. Although the impact ionization rate itself is strongly affected, little effect is observed on measurable quantities such as the impact ionization coefficient or the electron distribution function itself. [ABSTRACT FROM AUTHOR]

We present a method for microfabricating apertures in a silicon substrate using well-known cleanroom technologies resulting in highly reproducible giga-seal resistance bilayer formations. Using a plasma etcher, 150 μm apertures have been etched through a silicon wafer. Teflon™ has been chemically vapor deposited so that the surface resembles bulk Teflon and is hydrophobic. After fabrication, reproducible high resistance bilayers were formed and characteristic measurements of a self-inserted single OmpF porin ion channel protein were made. [ABSTRACT FROM AUTHOR]

We formulate a many-body model of transport in open quantum dots, which is based upon the idea of an enhanced electron-electron interaction in the vicinity of a quasibound state. Our studies suggest that the effect of including this peaked interaction is to increase the amplitude of the conductance fluctuations, beyond the value expected from a single-particle treatment. While the role of interactions in transport through open dots has attracted little theoretical attention, our results demonstrate the presence of interaction-induced corrections to the transport in these structures. [ABSTRACT FROM AUTHOR]

A correction to the article “Linear and nonlinear conductance of ballistic quantum wires with hybrid confinement” is presented.