We have measured the quantum critical behavior of the plateau-insulator (PI) transition in a low-mobility InGaAs/GaAs quantum well. The longitudinal resistivity measured for two different values of the electron density follows an exponential law, from which we extract critical exponents κ = 0.54 and 0.58, in good agreement with the value (κ = 0.57) previously obtained for an InGaAs/InP heterost...

The saturation of excitonic absorption in strained InGaAs/AlGaAs quantum wells is systematically measured as a function of strain. By comparison with an unstrained GaAs/AlGaAs quantum well sample a reduction by a factor of up to 9 in the saturation carrier density is observed in strained samples with indium concentrations of 10% ‘and 15%. Very low saturation densities, as low as 0.82X 1017 cmm3...

This thesis presents the characterization of tunnel junctions and tunnel-junction-coupled lasers. The reverse-biased leakage current in a tunnel junction can be exploited to tunnel electrons from the valence band of one active region to the conduction band of a second active region. Thus, tunnel-junction-coupled lasers are highly efficient as they allow electrons to stimulate the emission of ph...

We present a study on the effects of quantum dot coverage on the properties of InAs dots embedded in GaAs and in metamorphic In0.15Ga0.85As confining layers grown by molecular beam epitaxy on GaAs substrates. We show that redshifted emission wavelengths exceeding 1.3 μm at room temperature were obtained by the combined use of InGaAs confining layers and high quantum dot coverage. The use of hig...

Self-assembled InGaAs quantum dots (QDs) were fabricated inside a planar microcavity with two vertical cavity modes. This allowed us to excite the QDs coupled to one of the vertical cavity modes through two propagating cavity modes to study their down- and up-converted photoluminescence (PL). The up-converted PL increased continuously with the increasing temperature, reaching an intensity level...

Partly released, relaxed and wrinkled InGaAs membranes are used as virtual substrates for overgrowth with InAs. Such samples exhibit different lattice parameters for the unreleased epitaxial parts, the released flat, back-bond areas and the released wrinkled areas. A large InAs migration towards the released membrane is observed with a material accumulation on top of the freestanding wrinkles d...

CP measurements show that PBTI stress induced interface trap area density ΔNit in InGaAs/Al2O3 n-MOSFET is very small and has power law time evolution At in the stress phase, and is partially recovered in the recovery phase. However the DC Is-Vg measurements show large degradations of negative ΔVg and sub-threshold swing S in the sub-threshold region and are recovered in the recovery phase, als...

An avalanche photodiode (APD) based on an InGaAs/InGaAsP/InP structure containing separated absorption, charge and multiplication layers (SACM) was designed, fabricated and tested. The InGaAsP charge layer at the heterointerface between the InGaAs absorption and InP multiplication region allows optimization of the electric field distribution and suppression of the carrier capture at the heteroi...