Cross-sectional transmission electron microscopy (X-TEM) and scan-TEM are performed to study how the structural properties of InAs/GaAs quantum dots (QDs) are affected when capped by an InGaAs and InAlAs combination layer (CBL), which currently is one of the most promising active regions for a 1.3 microm QD laser. GaAs capping causes leveling of the QDs, which is suppressed by the introduction ...

Intersubband transitions from the ground state to the first and second excited states in pseudomorphic AlGaAs/lnGaAs/GaAs/ AlGaAs multiple step quantum wells have been observed. The step well structure has a configuration of two A1GaAs barriers confining an InGaAs/GaAs step. Multiple step wells were grown on GaAs substrate with each InGaAs layer compressively strained. During the growth, a unif...

Full-field optical coherence microscopy (FFOCM) is an interferometric technique for obtaining wide-field microscopic images deep within scattering biological samples. FFOCM has primarily been implemented in the 0.8 mum wavelength range with silicon-based cameras, which may limit penetration when imaging human tissue. In this paper, we demonstrate FFOCM at the wavelength range of 0.9 - 1.4 mum, ...

GaAs-InGaAs-AlGaAs Hall sensor, current source, differential amplifier, comparator and source follower were integrated to form the first highly sensitive, low power (~18 mW) III-V DC unipolar Hall integrated circuit. This is a three terminal device which utilises 2 μm gate length technology, offering very high yields, at least ~50% higher switching sensitivity (~ 6 mT) compared to existing comm...

This paper deals with Schottky and Heterostructure Barrier devices fabricated for planar integration in a 560 GHz Subharmonic Mixer (SHM). Taking advantage of an InP-based technology, two barrier types, metal/InGaAs and metal/InAlAs/InGaAs respectively, have been investigated. The design was carried out by means of self-consistent quantum calculations and the fabrication involved submicron Tsha...

We report on single rolled-up microtubes integrated with silicon-on-insulator waveguides. Microtubes with diameters of ~7 μm, wall thicknesses of ~250 nm, and lengths greater than 100 μm are fabricated by selectively releasing a coherently strained InGaAs/GaAs quantum dot layer from the handling GaAs substrate. The microtubes are then transferred from their host substrate to silicon-on-insulato...

A simple semi-phenomenological model, which accurately predicts the dependence of thresholdcurrent for temperature of Resonant-phonon three well quantum cascade laser based on verticaltransitions is offered. We found that, the longitude optical phonon scattering of thermally excitedelectrons is the most important limiting factor for thermal performance of high frequency THz QCLs.In low frequenc...

III-V compound multijunction solar cells enable ultrahigh efficiency performance in designs where subcells with high material quality and high internal quantum efficiency can be employed. However the optimal multijunction cell bandgap sequence cannot be achieved using lattice-matched compound semiconductor materials. Most current compound semiconductor solar cell design approaches are focused o...

Terahertz quantum cascade lasers based on InGaAswells and quaternary AlInGaAs barriers were measured inmagneticfield. This studywas carried out on a four-quantum-well active-region design with photon energy of 14.3meVprocessedwith bothAu andCuwaveguides. The heterostructure operates up to 148K at B= 0T in aCuwaveguide. The completemagneto-spectroscopic study allowed the comparison of emission a...

InAIAslInGaAs HFET’s fabricated by conventional mesa isolation have a potential parasitic gate-leakage path where the gate metallization overlaps the exposed channel edge at the mesa sidewall. We have unmistakably proven the existence of this path by fabricating special heterojunction diodes with different mesa-sidewall gate-metal overlap lengths. We find that sidewall leakage is a function of ...