Publications by Julien Dorsaz | EPFL Graph Search

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The growth of highly-reflective nitride-based distributed Bragg reflectors (DBRs) and their use in vertical cavity structures is reviewed. We discuss the various nitride material systems employed to design Bragg mirrors and microcavities, namely the Al-x(G ...

Gallium Nitride (GaN) and its ternary alloys with aluminium and indium have met a growing interest in the last decade. These semiconductors have a large direct bandgap and can be doped with either silicon (Si) for n-type and magnesium (Mg) for p-type layer ...

We report on the achievement of III-nitride blue superluminescent light-emitting diodes on GaN substrates. The epitaxial structure includes an active region made of In0.12Ga0.88N quantum wells in a GaN/AlGaN waveguide. Superluminescence under cw operation ...

We demonstrate state-of-the-art p-type (Al) GaN layers deposited at low temperature (740 degrees C) by ammonia molecular beam epitaxy (NH3-MBE) to be used as top cladding of laser diodes (LDs) with the aim of further reducing the thermal budget on the InGa ...

The authors report the realization of InGaN/GaN light emitting diodes (LEDs) with an electrical injection design suitable for vertical cavity surface emitting lasers. Controlled oxidation of an AlInN interlayer lattice matched to GaN allows confining the i ...

We demonstrate room-temperature continuous-wave operation of 425 nm InGaN-based blue laser diodes including a thin Al0.83In0.17N optical blocking layer. Structures are grown on c-plane GaN freestanding substrates with a lattice-matched AlInN layer position ...

Laser action with low threshold average pump power density (similar to 50 W. cm(-2)) at room temperature is reported for a crack-free planar vertical cavity surface emitting laser (VCSEL) structure based on a bottom lattice-matched AllnN/GaN distributed Br ...

We present a study on the dependence of the external Quantum Efficiency (QE) of Light Emitting Diodes (LEDs) on the device properties and p-contact metallisation. The external QE could be doubled by changing the p-type contact from oxidised Ni/Au to non-annealed Ag. The best value for the external QE of an unpackaged device is 13.5% and is obtained when the reflection from the Ag mirror contact is in phase with the QW emission.

We measure the charge carrier recombination coefficients of InGaN quantum wells by analyzing the dynamical properties of (Al,In)GaN laser diodes emitting in the violet spectral range. Relaxation oscillations and turn-on delays are fitted to a rate equation ...

We report on the growth by metalorganic vapor phase epitaxy of a InGaN/GaN resonant-cavity light emitting diode (RCLED) emitting at 454 nm and incorporating a 12-pair Al0.82In0.18N/GaN distributed Bragg reflector as bottom mirror. A(1-x)In(x)N layers with an Al content around x similar to 0.17 are lattice matched to GaN, thus avoiding strain-related issues in the subsequent active layers while keeping a high refractive index contrast of 7%, comparable to that achievable in the Al0.5Ga0.5N/GaN system. Device

Forward and reverse leakage currents in GaN/InGaN multi-quantum well light-emitting diodes (LEDs) are caused by reactive-ion etching (RIE) damages during device patterning. A method to recover the damaged surfaces, based on a chemical etch in KOH: ethylene ...

Highly selective oxidation of an AlInN interlayer buried in a GaN matrix is demonstrated. This technique was successfully applied to form current apertures in III-nitride light-emitting diodes (LEDs). GaN LEDs were grown by metal-organic vapor phase epitax ...

A report is presented on InGaN/GaN multiple quantum well laser diodes, grown by metal organic vapour phase epitaxy on c-plane sapphire substrates, including an Al0.83In0.17N cladding layer lattice-matched to GaN. Lasing action is demonstrated for gain-guid ...

We demonstrate hybrid laser diodes by combining n-type layers and an active region grown by metal organic vapor phase epitaxy with p-type layers grown by molecular beam epitaxy. These p-doped layers, grown at 740 degrees C, exhibit state-of-the-art electri ...

We report on the characteristics of blue superluminescent light emitting diodes based on the emission of InGaN quantum wells. Narrow ridge-waveguide devices realized by standard processing techniques and with extremely low facet reflectivity show single la ...

We report the growth over 2 in. sapphire substrates of crack-free fully epitaxial nitride-based microcavities using two highly reflective lattice-matched AlInN/GaN distributed Bragg reflectors (DBRs). The optical cavity is formed by an empty 3lambda/2 GaN ...

We report on the current properties of Al1-x InxN (x approximate to 0.18) layers lattice- matched ( LM) to GaN and their specific use to realize nearly strain- free structures for photonic and electronic applications. Following a literature survey of the g ...

High quality AlInN was grown near lattice-matched to GaN. It shows about 7% index contrast with GaN. AlInN is thus a promising alternative to AlGaN, as demonstrated by a 20-pairs AlInN/GaN distributed Bragg reflector with over 90% reflectivity. Light emitting diodes with active layers grown on top of AlInN/GaN multi-layers exhibit internal quantum efficiencies comparable to those of reference diodes grown directly on GaN buffer, this further demonstrate that AlInN material quality can meet the needs of opto

Very narrow spontaneous emission (Deltalambda similar to 0.5 nm), corresponding to a quality factor Q in excess of 800, has been obtained under continuous-wave excitation at room temperature with an AlInN/GaN monolithic microcavity. The structure is made o ...

We present a study on the improvement of the external Quantum Efficiency (QE) of Gallium-Nitride-based Light Emitting Diodes (LEDs) by the use of the Single Mirror (SMLED) design [N.E.J. Hunt et al., Electron. Lett. 28, 2169 (1992)]. Three different substrate emitting LEDs are compared by measurements and simulations. An increase in the external QE by more than a factor of two is demonstrated, due to the enhancement of the Light Extraction Efficiency for the SMLED design. Using the SMLED design leads to val

Julien Dorsaz

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Recent progress in the growth of highly reflective nitride-based distributed Bragg reflectors and their use in microcavities

Lattice-matched AlInN alloys for nitride-based optoelectronic devices

Broadband blue superluminescent light-emitting diodes based on GaN

Low temperature p-type doping of (Al)GaN layers using ammonia molecular beam epitaxy for InGaN laser diodes

Efficient current injection scheme for nitride vertical cavity surface emitting lasers

Emission characteristics of GaN-based blue lasers including a lattice matched Al0.83In0.17N optical blocking layer for improved optical beam quality

Blue lasing at room temperature in an optically pumped lattice-matched AlInN/GaN VCSEL structure

GaN-based single mirror light emitting diodes

Recombination coefficients of GaN-based laser diodes

InGaN/GaN resonant-cavity LED including an AlInN/GaN bragg mirror

Suppression of leakage currents in GaN-based LEDs induced by reactive-ion etching damages

Selective oxidation of AlInN layers for current confinement in III-nitride devices

Blue laser diodes including lattice-matched Al0.83In0.17N bottom cladding layer

InGaN laser diodes emitting at 500 nm with p-layers grown by molecular beam epitaxy

High Power Blue-Violet Superluminescent Light Emitting Diodes with InGaN Quantum Wells

Crack-free fully epitaxial nitride microcavity using highly reflective AllnN/GaN Bragg mirrors

Current status of AlInN layers lattice-matched to GaN for photonics and electronics

AlInN as high-index-contrast material for GaN-based optoelectronics

Lattice-matched distributed Bragg reflectors for nitride-based vertical cavity surface emitting lasers

GaN-based Single Mirror Light Emitting Diodes with high external quantum efficiency