Heat generation and dissipation in GaN-based light emitting devices

Figge, S.; Böttcher, T.; Hommel, D.; Zellweger, Christoph; Ilegems, M.

doi:10.1002/pssa.200303492

Cited by 23 publications

(12 citation statements)

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“…Although the quantum efficiency is strongly dependent on the temperature and therefore the operation current, its decrease can not be attributed to the increasing operation current as the increase of the electrical load during the ageing experiment is below 0.5 W, which should result into a heating of the active region by less than 5 K [4]. This temperature increase is to low to have such a high impact on the quantum efficiency.…”

Section: Lifetime Measurementsmentioning

confidence: 90%

Homoepitaxial laser diodes emitting at 390 nm and the influence of substrate quality

Figge

Dennemarck

Hommel

2007

Phys. Status Solidi (c)

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Section: Lifetime Measurementsmentioning

confidence: 90%

Homoepitaxial laser diodes emitting at 390 nm and the influence of substrate quality

Figge

Dennemarck

Hommel

2007

Phys. Status Solidi (c)

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“…This means that results of the simulation are close to situations of the ridge LDs. Details of the simulation can be found elsewhere [5]. Thermal resistance was slightly increasing because of smaller stripe width.…”

Section: Methodsmentioning

confidence: 99%

Study of ZnSe‐based green‐yellow ridge waveguide laser diodes toward long lifetime operation

Ueta

Klude

Gust

et al. 2004

phys. stat. sol. (c)

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Electro-optical characteristics of ridge and planar ZnSe-based laser diodes (LDs) were compared. Large reduction of threshold current densities for the ridge structure LDs was obtained. This can be attributed to the suppression of current spreading inside the LDs. Consequently, longer lifetimes of the ridge LDs under high duty cycle operation conditions over 10% were observed. Peak wavelengths for different duty cycle conditions between the ridge and the planar LDs were studied, and estimated temperatures in the active region for the ridge and the planar LDs under the CW operation with current densities near threshold were at +28.5 ºC and +66.2 ºC, respectively. Lower heat generation inside the ridge LDs elongated lifetimes of the LD strongly. Heat dissipations inside the structure for different stripe widths were simulated. Simulations predicted that generated heats inside the LD with a 2µm stripe width decreases by a factor of 3 compared to that with a 10µm stripe width. One of the approaches toward longer lifetimes is an introduction of ridge structures instead of gain-guiding planar structures, which were our ZnSe-based LDs up to now [1]. Generally, the gain-guiding planar LDs induce large threshold currents for laser operations because of the large current spreading inside the structure and weak lateral optical confinements. Excess heat generations inside the structure caused by large threshold current should enhance degradations of the devices. For the ridge structure, it is possible to control the current spreading and lateral optical confinements for small lateral width.In this work, ridge ZnSe-based LDs are compared to planar structures. To understand the difference of lifetimes between the planar and the ridge LDs, heat generations inside the LDs were simulated.

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“…The most promising way to push magnetic data storage to 1 TBit/in 2 is through thermally assisted magnetic recording in Co-based nanostructures [135]. Due to a phonon bottleneck, it is difficult to increase the frequency range of GaN microwave devices beyond 100 GHz [136]. Ultralow thermal conductivity materials can be used for thermal barrier coatings in jet engines [137], whereas extremely high thermal conductivities can be used for heat sinking [138].…”

Section: Exploring the Limits Of Thermal Transport In Nanostructured mentioning

confidence: 99%

A Review of Heat Transfer Physics

Carey

Chen

Grigoropoulos

et al. 2008

Nanoscale & Microscale Thermophysical Eng.

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With rising science contents of the engineering research and education, we give examples of the quest for fundamental understanding of heat transfer at the atomic level. These include transport as well as interactions (energy conversion) involving phonon, electron, fluid particle, and photon (or electromagnetic wave). Examples are 1. development of MD and DSMC fluid simulations as tools in nanoscale and microscale thermophysical engineering. 2. nanoscale thermal radiation, where the characteristic structural size becomes comparable to or smaller than the radiation (electromagnetic) wavelength. 3. laser-based nanoprocessing, where the surface topography, texture, etc., are modified with nanometer lateral feature definition using pulsed laser beams and confining optical energy by coupling to near-field scanning optical microscopes. 4. photon-electron-phonon couplings in laser cooling of solids, where the thermal vibrational energy (phonon) is removed by the anti-Stokes fluorescence; i.e., the photons emitted by an optical material have a mean energy higher than that of the absorbed photons.Nanoscale and Microscale Thermophysical Engineering, 12: 1-60, 2008 Copyright Ó Taylor 5. exploring the limits of thermal transport in nanostructured materials using spectrally dependent phonon scattering and vibrational spectra mismatching, to impede a particular phonon bands.These examples suggest that the atomic-level heat transfer builds on and expands electromagnetism (EM), atomic-molecular-optical physics, and condensed-matter physics. The theoretical treatments include ab initio calculations, molecular dynamics simulations, Boltzmann transport theory, and near-field EM thermal emission prediction. Experimental methods include near-field microscopy.Heat transfer physics describes the kinetics of storage, transport, and transformation of microscale energy carriers (phonon, electron, fluid particle, and photon). Sensible heat is stored in the thermal motion of atoms in various phases of matter. The atomic energy states and their populations are described by the classical and the quantum statistical mechanics (partition function and combinatoric energy distribution probabilities). Transport of thermal energy by the microscale carriers is based on their particle, quasi-particle, and wave descriptions; their diffusion, flow, and propagation; and their scattering and transformation encountered as they travel. The mechanisms of energy transitions among these energy carriers, and their rates (kinetics), are governed by the match of their energies, their interaction probabilities, and the various hindering-mechanism rate (kinetics) limits. Conservation of energy describes the interplay among energy storage, transport, and conversion, from the atomic to the continuum scales.With advances in micro-and nanotechnology, heat transfer engineering of micro-and nanostructured systems has offered new opportunities for research and education. New journals, including Nanoscale and Microscale Thermophysical Engineering, have allowed communi...

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Heat generation and dissipation in GaN-based light emitting devices

Cited by 23 publications

References 0 publications

Homoepitaxial laser diodes emitting at 390 nm and the influence of substrate quality

Homoepitaxial laser diodes emitting at 390 nm and the influence of substrate quality

Study of ZnSe‐based green‐yellow ridge waveguide laser diodes toward long lifetime operation

A Review of Heat Transfer Physics

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