This paper presents the design, fabrication and characterisation of InGaAs–InAlAs high electron mobility transistors (pHEMTs) suitable for low-frequency LNA designs. Very low levels of leakage, in the order of 0.05A/cm, are demonstrated by the pHEMTs, which have enabled the implementation of large-geometry, low-noise devices. Transistors with gate widths ranging from 200mm to 1.2mm are demonstr...

Helical tomotherapy is a dedicated intensity modulated radiation therapy (IMRT) system with on-board imaging capability (MVCT) and therefore differs from conventional treatment units. Different design goals resulted in some distinctive radiation field characteristics. The most significant differences in the design are the lack of flattening filter, increased shielding of the collimators, treatm...

This study examined the correlation between the off-state leakage current and dynamic on-resistance (RON) transients in AlGaN/GaN heterostructure field-effect transistors (HFETs) with and without a gate insulator under various stress conditions. The RON transients in a Schottky-gate HFET (SGHFET) and metal-insulator-semiconductor HFET (MISHFET) were observed after applying various amounts of dr...

The phase of a single quantum state is undefined unless the history of its creation provides a reference point. Thus, quantum interference may seem hardly relevant for the design of deterministic single-electron sources which strive to isolate individual charge carriers quickly and completely. We provide a counterexample by analyzing the nonadiabatic separation of a localized quantum state from...

Quantum logic gates are the key elements in quantum computing. Here we investigate the possibility of achieving a scalable and compact quantum computing based on stationary electron-spin qubits, by using the giant optical circular birefringence induced by quantum-dot spins in double-sided optical microcavities as a result of cavity quantum electrodynamics. We design the compact quantum circuits...

Dry dye-printing and solvent-enhanced dye diffusion were used to locally dope a previously spin-coated poly(9-vinylcarbazole) (PVK) polymer film with different dyes to fabricate side-by-side RGB OLED pixels. To reduce reverse leakage current and raise efficiency, a blanket tris-8-hydroxyquinoline aluminum (Alq) electron transport layer (ETL) was deposited over the polymer layer after the dye di...

1 Introduction GaN-based light-emitting diodes (LEDs) deliver the desired high efficiency only at relatively low injection current density [1]. At the elevated current densities required in practical high-brightness applications , the efficiency is substantially reduced. This efficiency droop phenomenon has been intensely investigated for a number of years, but the physical mechanisms behind it...

The authors analyse the performance and device physics of nitride laser diodes that exhibit the highest room-temperature continuous-wave output power. The analysis is based on advanced laser simulation. The laser model self-consistently combines band structure and freecarrier gain calculations with two-dimensional simulations of wave guiding, carrier transport and heat flux. Material parameters...

The dependence of the leakage current in 1.3m InGaAsP buried heterostructure (BH) lasers with p-n-p-n current blocking layers on well number, mesa width, and carrier density has been analyzed using a two-dimensional device simulator and compared with the electroluminescence (EL) emitted from InP layers. The analysis of the minority carrier flow reveals that the electron current flowing through ...

A new approach to intraoperative radiotherapy makes use of a mobile electron linear accelerator delivering therapeutic radiation doses in an operating room suite. This unconventional technology has raised questions concerning protection for personnel and the necessity of shielding the adjoining areas. In this study, the leakage and scatter radiation from the mobile electron accelerator is measu...