Gradual facet degradation of (Al,In)GaN quantum well lasers

Kümmler, V.; Lell, A.; Härle, V.; Schwarz, Uli; Schoedl, Thomas; Wegscheider, Werner

doi:10.1063/1.1704861

Cited by 19 publications

(13 citation statements)

References 12 publications

(8 reference statements)

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“…LDs with high light density, such as single‐mode narrow‐stripe LDs are more likely to be subject to COD . Gradual facet degradation via oxidation , semiconductor material decomposition or coating peeling , has also been reported, leading to slower decay. Facet degradation can be avoided by using broad‐area stripes to reduce the light intensity per unit facet area.…”

Section: State‐of‐the‐art Power‐conversion Efficiencies: Blue Ldsmentioning

confidence: 99%

Comparison between blue lasers and light‐emitting diodes for future solid‐state lighting

Wierer

Tsao

Sizov

2013

Laser & Photonics Reviews

492

244

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Solid‐state lighting (SSL) is now the most efficient source of high color quality white light ever created. Nevertheless, the blue InGaN light‐emitting diodes (LEDs) that are the light engine of SSL still have significant performance limitations. Foremost among these is the decrease in efficiency at high input current densities widely known as “efficiency droop.” Efficiency droop limits input power densities, contrary to the desire to produce more photons per unit LED chip area and to make SSL more affordable. Pending a solution to efficiency droop, an alternative device could be a blue laser diode (LD). LDs, operated in stimulated emission, can have high efficiencies at much higher input power densities than LEDs can. In this article, LEDs and LDs for future SSL are explored by comparing: their current state‐of‐the‐art input‐power‐density‐dependent power‐conversion efficiencies; potential improvements both in their peak power‐conversion efficiencies and in the input power densities at which those efficiencies peak; and their economics for practical SSL.

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Section: State‐of‐the‐art Power‐conversion Efficiencies: Blue Ldsmentioning

confidence: 99%

Comparison between blue lasers and light‐emitting diodes for future solid‐state lighting

Wierer

Tsao

Sizov

2013

Laser & Photonics Reviews

492

244

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“…Mirror facets are formed by cleaving along the common (1100) plane of GaN and SiC [11]. Most LDs are equipped with a high reflection mirror 1 0 99 R = .…”

Section: (Alin)gan On Sic Laser Diodesmentioning

confidence: 99%

“…by 4 l/ stacks of alternating SiO 2 and TiO 2 . One effect of the mirror coating is a reduced LD facet degradation [11][12][13]. Only the near-field scans were performed with uncoated LDs ( 1…”

Section: (Alin)gan On Sic Laser Diodesmentioning

confidence: 99%

Influence of ridge geometry on lateral mode stability of (Al,In)GaN laser diodes

Schwarz

Pindl

Sturm

et al. 2005

Physica Status Solidi (a)

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PACS 42.55.Px, 42.60.Lh, 78.45.+h Height and width of the ridge forming the laser diode waveguide determine threshold current density and lateral mode stability. We measure the optical near-field of the laser mode and simulate the twodimensional mode distribution including waveguide losses and optical gain. The simulations show that weak guiding and not current spreading is the major cause for increased threshold current densities in weakly guided laser diodes. The near-field measurements show fundamental and higher order modes for nominally identical ridge laser diodes. We demonstrate that asymmetric losses in the waveguide bias the lateral mode competition towards higher order modes for an intermediate range of index guiding. This asymmetric damping is specific for (Al,In)GaN laser diodes due to absorption introduced in the p-waveguide by magnesium doping. This competition of lateral modes can also be seen spectrally as two longitudinal mode combs of different optical gain.

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“…In addition, higher power red AlInGaP lasers for high speed digital video disc (DVD) applications will also benefit from increased performance and reliability due to the nitride facet process reported in this article. It is of interest also to notice in recent reports that even III-N (Al-Ga-In-Nitride) based lasers are sensitive to facet degradation and react to changes of operating atmosphere (from nitrogen to ambient air) when equipped with as cleaved facets [5][6][7] and also have a need of facet improvement. The suggested nitrogen based passivation process is applicable to all commonly used III-V materials systems (InAlGaP, InAlGaAs, InGaAsP, InGaAs, for telecom and industrial applications), III-N materials systems (GaN, AlGaN, InGaN, for optical memories, white and UV-light sources) and dilute nitrides (GaInNAs for future low cost telecom applications on GaAs substrates) and is applicable over the whole spectral range from below 300nm to beyond 2000nm.…”

Section: Introductionmentioning

confidence: 98%

Nitride facet passivation raises reliability, COMD, and enables high-temperature operation of InGaAsP, InGaAs, and InAlGaAs lasers

Silfvenius¹,

Sun²,

Blixt³

et al. 2005

SPIE Proceedings

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The laser diode technology, underpinning applications such as data storage, industrial lasers and optical telecommunications, still suffers from reliability and longevity limitations, especially in high power applications. A main problem for these lasers arises from facet oxidation, leading to increased absorption, power degradation and COMD device failure. Typically, high power devices initially show a low linear degradation and after some 100 hours, the degradation accelerates in a nonlinear fashion, indicating a degradation runaway condition. This article reports performance and reliability improvements that are based on a process which atomically seals surfaces and eliminates oxidation by forming stable nitrides on laser facets. The dangling bond terminating technology suppresses accelerated degradation associated with optical density and heat at laser facets. The dangling bond termination is demonstrated by improved COMD, decreased degradation at CW operation and a constant linear degradation rate at different QW temperature conditions (nonlinear degradation indicates advancement in the oxidation/optical absorption/facet heating/oxidation spiral). The technology is applicable to a range of material systems and has previously been demonstrated on InAlGaAs and InGaAs (increased COMD to >270 and 470mW/µm respectively). The devices with the typically lowest COMD levels (AlInGaAs) show a remarkably low linear degradation rate of <0.5%/kh during at CW life test operation at 90˚C and a power level corresponding to 80W bar power. In addition to long term AlInGaAs laser life test results, this paper presents results on nitride facet passivation applied to 805nm InGaAsP devices, showing improved COMD to 400mW/µm and the initial CW life data confirms the general behavior of the previously life-tested InGaAs and InAlGaAs based devices.

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Gradual facet degradation of (Al,In)GaN quantum well lasers

Cited by 19 publications

References 12 publications

Comparison between blue lasers and light‐emitting diodes for future solid‐state lighting

Comparison between blue lasers and light‐emitting diodes for future solid‐state lighting

Influence of ridge geometry on lateral mode stability of (Al,In)GaN laser diodes

Nitride facet passivation raises reliability, COMD, and enables high-temperature operation of InGaAsP, InGaAs, and InAlGaAs lasers

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