A5012515737- GaN-based semiconductor devices and materials
- Semiconductor Quantum Structures and Devices
- Semiconductor materials and devices
- Spectroscopy and Laser Applications
- Atmospheric Ozone and Climate
- Ga2O3 and related materials
- ZnO doping and properties
- Laser Design and Applications
- Metal and Thin Film Mechanics
- Photonic and Optical Devices
- Advanced Fiber Laser Technologies
- Photocathodes and Microchannel Plates
- Mechanical and Optical Resonators
- Solid State Laser Technologies
- 3D Printing in Biomedical Research
- Cellular Mechanics and Interactions
- Semiconductor Lasers and Optical Devices
- Nanowire Synthesis and Applications
- Semiconductor materials and interfaces
- Color Science and Applications
- Atmospheric and Environmental Gas Dynamics
- Photorefractive and Nonlinear Optics
- Light effects on plants
- Greenhouse Technology and Climate Control
- Impact of Light on Environment and Health
École Polytechnique Fédérale de Lausanne
2003-2022
Alpes Lasers (Switzerland)
2014-2016
The insertion of an InGaN underlayer (UL) is known to strongly improve the performance InGaN/GaN quantum well (QW) based blue light emitting diodes (LEDs). However, actual physical mechanism responsible for it still unclear. We thus conduct a systematic study and investigate different hypotheses. To this aim, single (S) QWs are grown on sapphire GaN free-standing substrates with or without UL. This allows us conclude that (i) improvement LED due higher internal efficiency SQW (ii) reduction...
Blue light-emitting diodes based on III-nitride semiconductors are nowadays widely used for solid-state lighting. They exhibit impressive figures of merit like an internal quantum efficiency close to 100%. This value is intriguing when considering the high dislocation density running throughout InGaN/GaN well (QW) active region. striking feature currently ascribed carrier localization occurring in InGaN alloy, which hinders their diffusion toward dislocations. However, it was recently...
Low phase noise lasers based on the combination of III-V semiconductors and silicon photonics are well established in near-infrared spectral regime. Recent advances development low-loss nitride-based photonic integrated resonators have allowed to outperform bulk external diode fiber both frequency agility 1550 nm-telecommunication window. Here, we demonstrate for first time a hybrid laser composed gallium nitride (GaN) chip-based microresonator operating at record low wavelengths as 410 nm...
We report on InAlN underlayer (UL) to improve the efficiency of near ultraviolet (NUV) light emitting diodes (LEDs). While InGaN UL is commonly used in high-efficiency blue LEDs it may absorb for shorter wavelengths. lattice-matched GaN exhibits a bandgap 4.6 eV. This allows alleviating absorption issues NUV LEDs. demonstrate that internal quantum 405 nm single InGaN/GaN well with ∼70% compared less than 10% without UL. Excellent I–V characteristics are achieved thanks polarization charge...
An indium-containing layer positioned underneath the InGaN/GaN quantum well (QW) active region is commonly used in high efficiency blue light-emitting diodes. Recent studies proposed that role of this underlayer to trap surface defects (SDs), which, otherwise, generate non-radiative recombination centers QWs. However, origin and nature these remain unknown. Our previous study revealed high-temperature growth GaN promotes SD creation. In work, we investigate impact GaN-buffer temperature on...
Defects can significantly modify the electro-optical characteristics of InGaN light-emitting diodes (LEDs); however, modeling impact defects on electrical LEDs is not straightforward. In this paper, we present an extensive investigation and InGaN-based LEDs, as a function thickness quantum well (QW). First, demonstrate that density in active region III-N scales with increasing QW. Since device layers high indium content tend to incorporate more defects, ascribed experimental evidence...
In this work, we demonstrate broad electrical tuning of quantum cascade lasers at 9.25 μm, 8.5 and 4.4 μm in continuous wave operation using Vernier-effect distributed Bragg reflectors based on superstructure gratings. Integrated micro-heaters allow to switch from one Vernier channel the other, while predictable mode-hop free can be obtained each modulating laser current with a side mode suppression ratio as high 30 dB. The resulting device behaves effectively switchable multicolour tunable...
We present single mode quantum cascade lasers including a microscopic heater for spectral emission tuning. Through the use of buried element, active region temperature can be modified without changing submount one. Emission frequency tuning in continuous-wave as large 9 cm(-1) at 1270 and 14 2040 are observed, corresponding to an increase temperatures ∼ 90 K. Due proximity heaters region, modulated several kHz range absence moving parts guarantees mechanical stability system. This method...
Abstract We report on InGaN edge emitting laser diodes with a top metal electrode located beside the ridge. Current spreading over ridge is achieved via highly doped n + -type GaN layer deposited of structure. The low sheet resistance -GaN ensures excellent lateral current spreading, while carrier injection confined all along thanks to tunneling at interface between and p ++ layer. Continuous-wave lasing 400 nm an output power 100 mW demonstrated uncoated facet devices threshold density 2.4...
Abstract Recent studies demonstrated that the performance of InGaN/GaN quantum well (QW) light emitting diodes (LEDs) can be significantly improved through insertion an InGaN underlayer (UL). The current working hypothesis is presence UL reduces density non-radiative recombination centers (NRCs) in QW itself: during growth UL, surface defects are effectively buried without propagating towards region. Despite importance this hypothesis, concentration profile wells LEDs with and was never...
Two types of near-UV light-emitting diodes (LEDs) with an InGaN/GaN single quantum well (QW) differing only in the presence or absence underlayer (UL) consisting InAlN/GaN superlattice (SL) were examined. The InAlN-based ULs previously shown to dramatically improve internal efficiency LEDs, via a decrease density deep traps responsible for nonradiative recombination QW region. main differences between samples and without UL (a) higher compensation Mg acceptors p-GaN:Mg contact layer sample...
We study the impact of non-radiative defects on Auger recombination in c-plane InGaN/GaN single quantum wells (SQWs) efficiency droop regime using high injection time-resolved photoluminescence. The defect density SQW is controlled by tuning thickness an InAlN underlayer. When increased, apart from Shockley–Read–Hall (SRH) and standard recombination, introducing extra defect-assisted process required to reconcile discrepancy observed between usual ABC model experimental data. derive a linear...
We investigate the density of defects and degradation rate in InGaN light-emitting diodes having identical dislocation epitaxial structure, but different indium content quantum well (QW; 12%, 16%, 20%). Our results, based on combined steady-state photocapacitance, light-capacitance voltage, measurements indicate that: (a) superlattice underlayer is for three wafers, indicating good reproducible growth conditions; (b) within active region devices shows a monotonic dependence QWs. These...
We present a detailed experimental investigation of the use novel actuator for frequency tuning and modulation in quantum cascade laser (QCL) based on resistive integrated heater (IH) placed close to active region. This new is attractive molecular spectroscopy applications as it enables fast QCL wavelength with minor influence optical output power, electrically-controlled. Using spectroscopic setup comprising low-pressure gas cell, we measured properties emitting at 7.8 μm function region IH...
We report on the evaluation of frequency stability a distributed feedback quantum cascade laser (QCL) at 8 μm that was continuously monitored over 2-month period using spectroscopic setup. The QCL operated in continuous wave mode room temperature (21.4 °C). It driven by home-made low-noise controller nominal current ~600 mA located middle its operation range. Two distinctive behaviors were observed. A monotonous drift about 1.8 GHz observed during slightly more than first month, followed...
Effects of 5 MeV electron irradiation on deep traps and electroluminescence from
Abstract We investigate the degradation mechanisms of In 0.2 Ga 0.8 N/GaN light emitting diodes through combined experimental analysis and simulations. The devices were submitted to constant current stress at 100 mA. Depending on measuring level, two trends observed: high test currents (e.g. 200 mA), a monotonic decrease in optical power was observed; low 5 an initial observed, followed by improvement device efficiency (positive ageing). For first time, such recovery effect analyzed modeled,...
We present for the first time an investigation of tuning and modulation properties a quantum cascade laser with integrated heater providing new mechanism. also show benefit spectroscopy applications.
We demonstrate for the first time a hybrid integrated low-noise laser composed of gallium nitride (GaN) based diode and silicon photonic chip microresonator operating at record low wavelengths as 410 nm in near ultraviolet wavelength region.
Flicker noise was studied in a set of 20 QCLs at 7-8 μm, showing significant differences among the devices and probable existence various sources. Ridge-waveguide lasers showed lower than buried-heterostructures.
We investigated the use of a novel actuator for frequency tuning and modulation in quantum cascade laser based on an integrated resistive heater. also show its benefit gas phase spectroscopy applications.