Prof. Pierre J. L. Gibart Profile

Prof. Pierre J. L. Gibart

Director of Research at CNRS

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Publications (5)

Proceedings Article | 28 August 2002 Paper

Epitaxial lateral overgrowth and other approaches for low-defect-density GaN/sapphire

Pierre Gibart, Bernard Beaumont

Proceedings Volume 10303, 1030307 (2002) https://doi.org/10.1117/12.482623

KEYWORDS: Epitaxial lateral overgrowth, Gallium nitride, Dielectrics, Heteroepitaxy, Epitaxy, Fabrication, Luminescence, Laser applications, Light sources, Laser liftoff

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Numerous defects are generated in the heteroepitaxy of GaN, with threading dislocations (TDs) being the most prevalent. A novel method of reducing the defect density has been the Epitaxial Lateral Overgrowth (ELO) technology, where parts of the highly dislocated starting GaN is masked with a dielectric mask, after which growth is restarted. At the beginning of the second step, deposition only occurs within the openings with no deposition observed on the mask. This is referred as Selective Area Epitaxy (SAE). The TDs are prevented from propagating into the overlayer by the dielectric mask, whereas GaN grown above the opening (coherent growth) keeps the same TDs density as the template, for at least during the early stages of the growth.

Currently, two main ELO technologies exist: the simpler one involves a single growth step after stripe opening. In this one-step-ELO (1S-ELO), growth in the opening remains in registry with the GaN template underneath (coherent part), whereas GaN over the mask extends laterally (wings). This leads to two grades, namely highly dislocated GaN above the openings, and low dislocation density GaN over the masks. With this technique, devices have to be fabricated on the wings. Therefore, conversely, in the two-step-ELO (2S-EL0) process, the growth conditions of the first step are monitored to obtain triangular stripes. Inside these stripes, the threading dislocations arising from the templates are bent by 90° when they encounter the inclined lateral facet. In the second step, the growth conditions are modified to achieve full coalescence. In this two-step-ELO, only the coalescence boundaries are defective.

In depth characterisation of these ELO GaN layers reveals that the intermediate stages of the process induce an inhomogeneous impurity incorporation and stress distribution. However, the ELO technology produces high quality GaN, with TDs densities in the mid 10⁶cn^-2, linewidths of the low temperature photoluminescence (PL) near band gap recombination peaks below 1 meV, and deep electron traps concentration below 10¹⁴cm^-3 (compared to mid 10¹⁵cm^-3 in standard GaN). To further reduce the TDs density, multiple step ELO have also been implented.

For applications such as read/write laser light sources of digital versatile disks, higher power and longer operation lifetimes are required, thus necessitating the production of better quality material. Several options are also currently available to pave the way towards self supported high quality GaN. These technologies involve growing thick GaN layers (possibly on MOVPE ELO GaN) and then separating the layers from the substrate. HVPE has proven to be a reliable method to grow GaN with growth rates ranging from 30 to 100 pm/hour. In thick layers (several hundred μm), the mecanisms used for the reduction of dislocations become more efficient. Separation from the starting substrate is currently achieved by either laser lift off, chemically or by strain induced.

Proceedings Article | 13 April 2000 Paper

AlGaN-based structures on sapphire for visible blind Schottky-barrier UV photodetectors: toward high-performance device applications

Franck Omnes, Eva Monroy, Bernard Beaumont, Fernando Calle, Elias Munoz Merino, Pierre Gibart

Proceedings Volume 3948, (2000) https://doi.org/10.1117/12.382124

KEYWORDS: Gallium nitride, Photodiodes, Photodetectors, Ultraviolet radiation, Aluminum, Sapphire, Visible radiation, Semiconductors, Sensors, Radiation effects

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Proceedings Article | 8 April 1999 Paper

Metal organic vapor phase epitaxy of GaN and lateral overgrowth

Bernard Beaumont, Pierre Gibart

Proceedings Volume 3725, (1999) https://doi.org/10.1117/12.344707

KEYWORDS: Gallium nitride, Nitrogen, Sapphire, Magnesium, Plasma, Vapor phase epitaxy, Epitaxy, Light emitting diodes, Thermodynamics, Reflectivity

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Proceedings Article | 7 April 1999 Paper

AlGaN-based photodetectors for solar UV applications

Elias Munoz Merino, E. Monroy, Fernando Calle, Miguel Sanchez, Enrico Calleja, Franck Omnes, Pierre J. Gibart, Francisco Jaque, Inigo Aguirre de Carcer

Proceedings Volume 3629, (1999) https://doi.org/10.1117/12.344557

KEYWORDS: Ultraviolet radiation, Aluminum, Sensors, Photodiodes, Photodetectors, Silicon, Solar radiation, Photoresistors, Gallium nitride, Ultraviolet detectors

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Proceedings Article | 1 February 1991 Paper

Bistability of the Sn donor in AlxGa1-xAs and GaAs under pressure studied by Mossbauer spectroscopy

Pierre Gibart, Don Williamson

Proceedings Volume 1362, (1991) https://doi.org/10.1117/12.24497

KEYWORDS: Tin, Electrons, Gallium arsenide, Optoelectronic devices, Doping, Chemical species, Aluminum, Physics, Semiconductors, Spectroscopy

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