SEMOND , Fabrice

Self-assembled semiconductors QDs are of great interest in fundamental physics as well as inapplied physics. In GaN/AlN heterostructures, the huge band-offset and the strong excitonicbinding lead to an important exciton confinement allowing an emission even at roomtemperature. GaN QDs grown along the (1000) axis are named "polar" due to their...

In this paper, a performance comparison between sub-micron thick AlGaN/GaN and AlN/GaN HEMT devices are reported. Various gate lengths have been employed in order to analyze the impact on DC and RF performances. Electrical characteristics of these structures for 100 nm gate length show a higher maximum drain current, extrinsic transconductance...

International audience

Properties of self-assembled quantum dots (QDs), often referred to as artificial atoms in solid state, are very interesting in order to study physical effects specific to single quantum systems such as the single-photon emission. Thanks to their huge vertical quantum confinement, GaN QDs are emitting even at room temperature and on a large UV...

GaN high electron mobility transistors (HEMT) are becoming the mainstream for high frequency and power switching applications. Devices and circuits based on these emerging materials are more suited to operate at higher voltages and temperatures than Si-based devices owing to their superior physical properties. Recently, AlGaN/GaN based high...

International audience

Properties of self-assembled quantum dots (QDs), often referred to as artificial atoms in solid state, are very interesting in order to study physical effects specific to single quantum systems such as the single-photon emission. Thanks to their huge vertical quantum confinement, GaN QDs are emitting even at room temperature and on a large UV...

We report on a sub-micron thick AlGaN/GaN high electron mobility transistor (HEMT) epilayers grown on silicon substrate with a state-of-the art vertical buffer breakdown field as high as 6 MV/cm enabling a high transistor breakdown voltage of 250 V for short gate to drain distances despite such a thin structure. HEMTs with a gate length of 100...

MBE has several advantages for the epitaxy of GaN-based heterostructures. More specifically, by controlling the interface between the AlN buffer layer and the silicon substrate, ammonia-MBE allows to grow innovative structures on silicon. Epitaxy on silicon necessarily requires a demonstration of scaling-up on large wafers used by the...

In this work, sub-micron-thick AlN/GaN transistors (HEMTs) grown on a silicon substrate for high-frequency power applications are reported. Using molecular beam epitaxy, an innovative ultrathin step-graded buffer with a total stack thickness of 450 nm enables one to combine an excellent electron confinement, as reflected by the low...

International audience

Les boîtes quantiques GaN présentent des propriétés de confinement très attrayantes, jusqu'à 300K. De nombreux développements récents ont montré qu'elles peuvent se comparer favorablement aux boîtes quantiques antérieures et mieux maîtrisées, InAs et CdTe en particulier. Mais l'étude de la structure fine des complexes excitoniques dans les...

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We report on polarization-resolved micro-photoluminescence experiments performed on a single GaN/AlN polar quantum dot (QD) grown on Si(111) substrate. We have performed a systematic study of about 50 QDs. The emission of about half of the QD excitons is strongly linearly polarized, up to 90%. Such a polarization is known to be the...

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We present single dot spectroscopy of hexagonal GaN/AlN self‐assembled quantum dots (QDs) grown by MBE along the (0001) axis. The GaN quantum dots are grown on an AlN epilayer on Si (111) substrate, with dot densities between 108 and 1011 cm−2. We study the micro‐photoluminescence spectra of a few quantum dots. In the energy range corresponding...

We report microphotoluminescence studies of single GaN/AlN quantum dots grown along the (0001) crystal axis by molecular-beam epitaxy on Si(111) substrates. The emission lines exhibit a linear polarization along the growth plane but with varying magnitudes of the polarization degree and with principal polarization axes that do not necessarily...

We report microphotoluminescence studies of single GaN∕AlN quantum dots grown by molecular beam epitaxy on Si(111) substrates. Small groups of emission lines characterize each single dot, with linewidths mostly limited by our experimental setup to 1 or 2meV. By using time-dependent microphotoluminescence, we observe both the continuous and...

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The polariton emission in a microcavity is usually measured from the surface, and little is known about the actual role of guided modes below the light cone in air, that can couple to the exciton transition, collect part of the emission and contribute to polariton losses. In this work we investigate a ZnO planar microcavity with mesas. The...

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Grâce à une nouvelle combinaison des modes de croissances EJM et MOCVD nous avons réalisés des guides d'onde à base d'AlN et de GaN mono-cristalins sur saphir qui présentent de très faibles pertes à la propagation. Nous avons pu démontrer que ces guides ont des possibilités très intéressantes de doublage de fréquence dans le proche IR et le...

In this paper, AlN-based HEMTs on silicon are demonstrated using NH3-MBE. The spirit is to get the highest 2DEG density theoretically achievable in nitrides while keeping thin barrier thickness, which is mandatory to achieve high frequency performances. To do that, the strategy consists in growing a relaxed AlN ...

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