Light extraction from a light emitting diode with photonic structure in the surface layer investigated by NSOM

Pudiš, Dušan; Suslik, Lubos; Škriniarová, J.; Kováč, J.; Martinček, Ivan; Hašc̆ı́k, Š.; Kubicova, Ivana; Novák, J.; Veselý, M.

doi:10.1016/j.optlastec.2011.01.004

Cited by 15 publications

(10 citation statements)

References 21 publications

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“…Similar results were shown for GaAs-based structures, where the L(I) measurements demonstrated an enhancement of light extraction efficiency between the emitted light of the PhC and non-PhC LED app. 1.39 times [10]. For the same structure, the effect of 2D structure on the light extraction efficiency was documented from analysis in the near field of the PhC LED, where the analysis revealed 15% enhancement of the emission from the air hole regions in comparison with the surrounding surface.…”

Section: Resultsmentioning

confidence: 94%

“…On the other hand, PhC structures have also been investigated as a potential candidate for improving the extraction efficiency of LEDs [7][8][9][10]. While geometric factors of the 2D PhC structure -such as lattice shape, air hole size, and dielectric constants of used materials -play a role in determining the directionality and the far-field profile; for the light extraction efficiency the etch depth is important [11].…”

Section: Introductionmentioning

confidence: 99%

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Irregular 2D structure in the light emitting diode surface patterned by NSOM lithography

et al. 2012

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In this paper, we present near-field scanning optical microscope (NSOM) in illumination mode as effective tool for semiconductor device surface patterning. In the illumination mode, the non-contact mode of the NSOM lithography is performed, where the fiber probe exposes defined spots in thin photoresist layer. As the scanning technique allows irregular two-dimensional patterning of different surfaces, this was applied on the GaAs/AlGaAs based light emitting diode surface. Patterned surface was analyzed by optical microscope and atomic force microscope.Keywords-near-field scanning optical microscope lithography, irregular 2D structure, light emitting diode surface patterning, photonic structure.

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Section: Resultsmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Irregular 2D structure in the light emitting diode surface patterned by NSOM lithography

et al. 2012

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“…One-dimensional optical field was formed by the interference of two coherent beams of Ar ion laser (488 nm) with the intensity 60 mW/cm 2 . The adequate exposure time for this experiment was optimized to 100-120 s [10]. 2D square pattern in the 250 nm thin photoresist layer was achieved using the double exposure process [8,10].…”

Section: Methodsmentioning

confidence: 99%

“…The adequate exposure time for this experiment was optimized to 100-120 s [10]. 2D square pattern in the 250 nm thin photoresist layer was achieved using the double exposure process [8,10]. The patterned photoresist masks were used for formation of 2D PhC structures in the LED surface using reactive ion etching (RIE).…”

Section: Methodsmentioning

confidence: 99%

“…The patterned photoresist masks were used for formation of 2D PhC structures in the LED surface using reactive ion etching (RIE). RIE was processed in CCl 4 /He based plasma in a ROTH & RAU MICROSYS 350 machine for time 150 s [10]. Periodicity and homogeneity of patterned LED surface were investigated by scanning electron microscope (SEM), atomic force microscope (AFM).…”

Section: Methodsmentioning

confidence: 99%

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Emission and absorption properties of patterned LED with 2D PhC

Suslik

Pudiš

Škriniarová

et al. 2012

The Ninth International Conference on Advanced Semiconductor Devices and Mircosystems

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Photonic crystals (PhC) create platform for a new generation of optical and optoelectronical devices. The PhC structures have been patterned in GaAs-based light emitting diodes in order to modify their optical properties. Patterned diodes with two-dimensional PhC were investigated by measurements of emission and detection properties. Measured dependencies revealed effect of PhC on emission and photocurrent spectrum. IntroductionPhotonic crystals (PhC) push the limits of conventional optoelectronical devices and create platform for a new generation of components of integrated optoelectronics. The PhC structures have been recently employed as a way how to improve the light extraction efficiency (LEE) in light emitting diodes (LED) and modify the far-field pattern diagram [1][2][3]. LEE enhancement can be achieved by minimizing the total internal reflection in the diode surface by surface roughness or photonic band gap effect [4][5][6]. In case of large period structures, the PhCs work as a diffraction grating placed directly on the light source. Short period structures can generate a photonic band gap where photons with frequencies within the gap are not allowed to propagate, resulting in an enhancement of light extraction in the vertical direction from a LED [6]. Also these short period structures are able to modify the far-field pattern diagram [3].In this work we focus on fabrication of two-dimensional (2D) PhC structures prepared in LED surface with aim to modify far-field pattern diagram and to improve LEE from the LED surface. Conventional GaAs/AlGaAs based LED with triple quantum well in active region emitting at central wavelength of 850 nm was used [7]. The LED surface was patterned with 2D PhC of square symmetry and the effect of PhC on optical properties was analysed. ExperimentalThe LED structures were grown by low pressure metal organic vapor phase epitaxy on (001) oriented n-GaAs substrate. The LED structure consists of 800 nm n-doped Al 0.295 Ga 0.705 As confinement layer, the undoped quantum well (QW) active region and 1300 nm p-doped upper confinement Al 0.295 Ga 0.705 As layer. The structure was covered by 40 nm GaAs cap layer (Fig. 1a). The QW active region contains three 9 nm thick GaAs quantum wells separated by 24 nm thick Al 0.295 Ga 0.705 As barriers.

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Effect of 2D photonic structure patterned in the LED surface on emission properties

Pudiš

Suslik

Škriniarová

et al. 2013

Applied Surface Science

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Light extraction from a light emitting diode with photonic structure in the surface layer investigated by NSOM

Cited by 15 publications

References 21 publications

Irregular 2D structure in the light emitting diode surface patterned by NSOM lithography

Irregular 2D structure in the light emitting diode surface patterned by NSOM lithography

Emission and absorption properties of patterned LED with 2D PhC

Effect of 2D photonic structure patterned in the LED surface on emission properties

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