Publications de Marc Ilegems | EPFL Graph Search

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A high-reflectance GaInP/GaAs distributed Bragg reflector (DBR) was grown by chemical beam epitaxy (CBE). The mirror consists of 40 pairs of alternating layers and was designed for a centre wavelength of 980 nm, resulting in a total thickness of 5.8 mum. Highly stable growth conditions led to a maximum reflectance of 0.99 and to a variation in the centre wavelength of only 5 nm over the 2'' (50.8 mm) wafer. Transmission electron microscopy and X-ray diffraction measurements confirmed the vertical uniformity

The emission properties of self-assembled InAs quantum dots (QDs) and lattice-matched GaInNAs quantum wells (QWs) emitting around 1.3 mum were investigated by temperature-dependent and time-resolved photoluminescence (PL). The QDs have much higher PL efficiency at low excitation, but saturate faster as the excitation is increased, due to the lower density of states. Lifetime measurements show that nonradiative recombination plays a more important role in the GaInNAs QW than in QDs. (C) 2002 American Institu

Valence- and conduction-band offsets can be induced at GaAs(100) polar homojunctions by means of ultrathin Si intralayers. The microscopic interface dipole responsible for the creation of such offsets can be varied by changing the Si intralayer thickness; the consequently variable band discontinuities represent a tunable parameter with potential applications in band-gap engineering. Even though the existence and the direction of these discontinuities are in agreement with theoretical predictions, the existi

We studied the influence of the growth temperature Ts and of the InGaAs quantum-well channel thickness dch on the 300 and 77 K Hall electrical properties of pseudomorphic MODFET-type heterostructures grown by molecular-beam epitaxy (MBE). In agreement with Nguyen et al., we find an optimum channel thickness of 90 Å for an indium composition y = 0.25 of the channel. Significant improvements in sheet resistivity ϱs and in carrier concentration nso were obtained by using AlGaAs doped barriers on both sides of

Al0.3Ga0.7As:Si/GaAs modulation-doped field-effect transistor-type heterostructures were grown using two different growth temperatures (500 and 620 degrees C) and three doping modes (delta-doping, pulse-doping, and uniform-doping). Deep level transient spectroscopy (DLTS) measurements were performed on these structures using a new Fourier-analysis method. Up to four DLTS peaks, related to the different possible configurations of the nearest Al and Ga neighbors around each DX site, were observed. Both the gr

We have studied the effect of growth interruptions on 2 monolayer thick InAs/InP strained quantum wells (QWS) grown by chemical beam epitaxy. The main feature is the formation of up to 8 monolayer thick InAs islands during As, annealing of the QW. Their formation is characterized by a two- to three-dimensional transition of the reflection high energy electron diffraction (RHEED) pattern and by multiple-line photoluminescence spectra. This interpretation of the data is confirmed by transmission electron micr

We have studied the effect of growth interruptions on 2-monolayers-thick InAs/InP strained quantum wells (QW) grown by chemical beam epitaxy. The main feature is the formation of up to 8-monolayers-thick InAs islands during As2 annealing of the QW. Their formation is characterized by a two to three dimensional transition of the reflection high-energy electron diffraction pattern and multiple-lines photoluminescence spectra. An increase of a short range roughness at the InP-InAs interface due to As2 annealin

The accumulation of oxygen at GaAs/AlGaAs interfacesgrown by molecular beam epitaxy has been established by secondary ion mass spectrometry profiling of GaAs/AlGaAs multilayerstructures. An enhanced oxygen peak was observed at the boundary between GaAs and Al x Ga1−x As layers with x=0.35 and x=1 when the binary layer is deposited on top of the ternary layer. The segregation of oxygen may be a contributing factor responsible for the lower luminescence reported in the first GaAs well of multilayerquantum wel

Low-frequency noise (LFN) characteristics of dry-and wet-etched InAlAs/InGaAs HEMTS have been studied. It is found that due to passivation of deep traps by hydrogen the excess LFN (1/f and G-R) in dry-etched HEMTs is significantly lower than in wet-etched devices. All the traps as detected by LFN were found to be located in the InAlAs barrier layer.

The indium desorption rates from InGaAs and InAlAs grown on InP substrates have been measured by wedge transmission electron microscopy as a function of the growth temperature. Desorption becomes significant at 545-degrees-C for both materials. No automatching effects could be observed under the growth conditions of the experiment. The bandgap of In(y)Al1-yAs has been measured at 77 K as a function of the indium content. The composition and the strain have been measured by four-crystal high resolution X-ray

A thin InAs layer grown in a quasi-two-dimensional film over InP reorganizes into islands if left to anneal under arsine. This surface transformation is inhibited at lower arsine fluxes. With increasing temperature, the surface transformation is activated as long as the effective arsine coverage is sufficient.

The intermixing process of ultrathin InAs/InP strained quantum well structures by thermal annealing at 730-830-degrees-C is investigated by photoluminescence measurements. Analyzing the results using a microscopic model, the interdiffusion process is characterized by an activation energy close to 3.8+/-2.0 eV, leading to an interdiffusion coefficient close to 7+/-0.5x10(-7) cm2/s at 830-degrees-C.

Marc Ilegems

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High-reflectance GaInP/GaAs distributed Bragg reflector

Comparison of radiative properties of InAs quantum dots and GaInNAs quantum wells emitting around 1.3 mu m

Artificial Band Discontinuities at GaAs Homojunctions

MBE growth and characterization of MODFET heterostructures using pseudomorphic InGaAs or InAs/GaAs superlattice channels

Investigation of DX centers in modulation-doped field-effect transistor-type Al0.3Ga0.7As/GaAs heterostructures using a fourier-transform deep level transient spectroscopy system

Effect of growth interruptions on ultra thin InAs/InP quantum grown by chemical beam epitaxy

Island formation in ultra-thin InAs/InP quantum wells grown by chemical beam epitaxy

Secondary ion mass spectrometry study of oxygen accumulation at GaAs/AlGaAs interfaces grown by molecular beam epitaxy

Low-frequency Noise Characterization of Dry-etched and Wet-etched InAlAs/InGaAs HEMTs

Characterization of InGaAs and InAlAs layers on InP by four-crystal high resolution X-ray diffraction and wedge transmission electron microscopy

Dynamics of island formation in the growth of InAs/InP quantum wells

As/P interdiffusion in ultrathin InAs/InP strained quantum wells

Nonlinear reflectivity of strongly coupled exciton-photon systems under resonant and non-resonant pumping

Microscopic evidence of point defect incorporation in laterally overgrown GaN

Influence of the device-width on the accuracy of quantization in the integer quantum Hall effect

Collisional broadening of semiconductor microcavity polaritons

On device simultaneous determination of the source and cavity parameters of a microcavity Light-Emitting Diode

Infiltration of planar photonic crystals with liquid crystals

Structural and electrooptical characteristics of quantum dots emitting at 1.3 µm on Gallium Arsenide

Measurement of cavity polariton dispersion curve