In-situ observation of lateral AlAs oxidation and dislocation formation in VCSELs

Fabbro, Robert; Coppeta, Raffaele; Pusterhofer, Michael; Fasching, G.; Haber, Thomas; Grogger, Werner

doi:10.1016/j.micron.2022.103264

Cited by 5 publications

(4 citation statements)

References 20 publications

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“…with 𝛿 introduced as a coefficient to match the dimension on the two sides of ( 9). These assumptions are reasonable because the defect is a direct result of lattice displacement and the stress is the driving force of defect generation, as reported by previous experimental studies [4], [5], [6], [7]. It is worth noting that unlike the scalar quantity 𝜌 in (5) that defines the probability of the defect at a specific location at certain step, the vectorial quantity 𝝆 = [𝜌 𝑖 ] 1×3 defines the probability of the defect's random walking direction from one step to the next.…”

Section: A Anisotropic Defect Random Walkingsupporting

confidence: 53%

“…With increasing emphasis on device lifetime and failure rate, reliability is a crucial issue for practical VCSEL applications. Research has revealed that dark line defects are the primary cause of failure in GaAs-based oxide confined VCSELs [4], [5], [6], [7]. These defects are generated due to the excessive mechanical stress on the oxide layer formed by the oxidation of Manuscript received March 19, 2024.…”

Section: Introductionmentioning

confidence: 99%

“…Among the many research works on VCSEL's reliability and failure analysis, some relevant studies have been reported by reference [4], [5], [6], [7], [10], [11], [12], [13]. Although analyses on the root cause and intrinsic mechanism of defect formation and expansion were mainly based on theoretical speculations [4], these studies managed to provide several possible degradation modes of VCSELs and explained the nature of defects, their origin, and potential mechanisms of their expansion.…”

Section: Introductionmentioning

confidence: 99%

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Dynamic Modeling of Stress-Induced Defect Expansion in VCSELs

Zhang,

Li,

Zhao

2024

IEEE Photonics J.

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Many failures of semiconductor-based oxide confined vertical cavity surface emitting lasers (VCSELs) are closely related to the generation and expansion of defects in the device structure. However, existing research has predominantly focused on the static study of defect morphology, with little attention given to analyzing the dynamic process of defect expansion, which limited our ability to predict device random failures due to lack of understandings on defect generation and expansion. To address this issue, we present a macroscopic phenomenological evolution model that describes the dynamic expansion of defects in VCSELs, in which the expansion of defects is treated as an anisotropic lattice strain diffusion process. We further exploit a diffusion-limited aggregation (DLA) method in solving the diffusion equation, which describes the random propagation and aggregation of strain in the vicinity of highly strained areas, resulting in defect formation when the stress from accumulated strain surpasses the bonding force of the atoms in the lattice. Our simulation result manages to replicate the dendritic expansion morphology of defects, aligning with experimental observations very well. Our model also predicts an accelerated defect expansion process, which is again consistent with the experimental result. This model finds relevance in applications such as random failure prediction through device aging, burn-in condition setting in device screening, and device structural and/or material design improvement for mitigating defect expansion.

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Section: A Anisotropic Defect Random Walkingsupporting

confidence: 53%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dynamic Modeling of Stress-Induced Defect Expansion in VCSELs

Zhang,

Li,

Zhao

2024

IEEE Photonics J.

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“…Both of this cases can be seen in data reported by Ochiai et al [46], which allows the assignment of oxidation regimes to others data depending on the temperature dependent oxidation speed. In figure 7 multiple models are plotted and it can be seen that the data reported by Ko et al [47] exhibits a diffusion limited behavior whereas the data provided by Fabbro et al [48] is in the reaction limited regime as only short oxidation lengths have been observed. When comparing the models with the estimated oxidation speed of the stress test temperatures of 335 • C-460 • C are predicted.…”

Section: Oxidation Ratesmentioning

confidence: 90%

Electrical-stress driven oxidation in 940 nm oxide-confined VCSEL

Pusterhofer¹,

Fabbro²,

Coppeta³

et al. 2021

Semicond. Sci. Technol.

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In this work, accelerated stress tests have been performed on oxide confined vertical cavity surface emitting LASER arrays to study the formation of defects degrading the performance of the device. One such defect is an additional oxide volume forming at the oxide aperture edge, which is used for optical and electrical confinement. After producing an additional oxide volume the sample was investigated using transmission electron microscopy to estimate the oxidation speed. To produce further insights into the formation process, the temperature during such a stress test was estimated by experimentally measuring the thermal resistance, and by a thermodynamic transport simulation. Both methods produced very similar results showing a temperature increase of around 22 K for a dissipated power of 3.5 mW per emitter. However this temperature rise is very small when compared to oxidation models found in literature and should not be enough to promote the oxidation. This indicates the presence of a new enhanced oxidation mechanism, which could be connected to corrosion based failure mechanisms reported in literature.

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