Structural Modifications in Free-Standing InGaN/GaN LEDs after Femtosecond Laser Lift-Off

Bornemann, Steffen; Yulianto, Nursidik; Meyer, Tobias; Gülink, Jan; Margenfeld, Christoph; Seibt, M.; Wasisto, Hutomo Suryo; Waag, A.

doi:10.3390/proceedings2130897

Cited by 4 publications

(2 citation statements)

References 6 publications

(8 reference statements)

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“…Although the InGaN/ GaN MQW layers were still in a good condition (i.e., no significant defect was shown), a damage still appeared within the n-GaN layer, which is at ∼2 μm from the fs-LLO-released interface. This result is similar to those obtained in other previously reported LLO cases, 33,68,69 in which the location of structural defects or damages depends on the used laser pulse width and its absorption coefficient of GaN. One of the studies related to structural damages occurring in LLO processes has demonstrated that a laser possessing a higher absorption coefficient of GaN will yield shallower penetration depth (e.g., a 248 nm KrF excimer laser with a pulse time of 35 ns).…”

Section: Resultssupporting

confidence: 90%

Ultrashort Pulse Laser Lift-Off Processing of InGaN/GaN Light-Emitting Diode Chips

Yulianto

Kadja

Bornemann

et al. 2021

ACS Appl. Electron. Mater.

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Gallium nitride (GaN) film delamination is an important process during the fabrication of GaN light-emitting diodes (LEDs) and laser diodes. Here, we utilize 520 nm femtosecond laser pulses, exploiting nonlinear absorption rather than single-photon absorption such as in conventional laser lift-off (LLO) employing excimer or Q-switched laser sources. The focus of this study is to investigate the influence of laser scanning speed and integrated fluence corresponding to laser energy per area during the LLO processing of GaN LED chips and their resulting structural properties. Because both the sapphire substrate and InGaN/GaN heterostructures are fully transparent to the emission of the laser system, a key question is related to the impact of laser pulses on the quality of a thin film structure. Therefore, several characterization methods (i.e., scanning electron microscopy, atomic force microscopy, X-ray diffraction, Raman spectroscopy, and electroluminescence spectroscopy) were employed to understand the material modifications made by femtosecond LLO (fs-LLO). We demonstrated that by adjusting the laser scanning speed, smooth GaN surfaces and good crystal quality could be obtained regardless of the existing delamination of metal contact, which then slightly downgraded the LED performance. Here, the integrated fluence level was set in the range of 2.6–4.4 J/cm2 to enable the fs-LLO process. Moreover, two mitigation strategies were developed and proven to improve the optoelectrical characteristics of the lifted-off LEDs (i.e., modification of the processing step related to the metal creation and reduction of laser energy).

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Section: Resultssupporting

confidence: 90%

Ultrashort Pulse Laser Lift-Off Processing of InGaN/GaN Light-Emitting Diode Chips

Yulianto

Kadja

Bornemann

et al. 2021

ACS Appl. Electron. Mater.

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“…Laser processing is at the forefront of technology in the display industry; lasers enable mass production of the most demanding tasks [4]. They enable the cutting of substrates, fine patterning, low-temperature polycrystalline silicon (LTPS) annealing [5], temporary carrier delamination (laser lift-off) for flexible displays [6], and more. Laser processing offers several opportunities for MicroLED display production:…”

Section: Laser Applications In Microled Manufacturingmentioning

confidence: 99%

67‐3: Numerical Simulation for GaN‐based MicroLED Laser Induced Forward Transfer (LIFT) and Comparison With Real‐Time Measurements of the Flight Phase

Eppelt,

Fatahilah,

Brune

et al. 2023

Symp Digest of Tech Papers

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The use of pulsed UV laser systems to manipulate MicroLEDs is enabling the development and production of MicroLED displays. For this purpose, modeling and numerical simulations are useful as they offer an insight into the process that is impossible to achieve by process diagnostic methods alone. The multi‐physics and non‐linear radiation‐material interactions that occur in laser processing of MicroLEDs can be evaluated, visualized, and brought into line with the observed processing results. We present our most current attempts to do real‐time measurements during the flight phase as well as findings in numerical simulation of MicroLED LIFT.

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Beyond solid-state lighting: Miniaturization, hybrid integration, and applications of GaN nano- and micro-LEDs

Wasisto

Prades

Gülink

et al. 2019

Applied Physics Reviews

226

116

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Gallium nitride (GaN) light-emitting-diode (LED) technology has been the revolution in modern lighting. In the last decade, a huge global market of efficient, long-lasting, and ubiquitous white light sources has developed around the inception of the Nobel-prize-winning blue GaN LEDs. Today, GaN optoelectronics is developing beyond solid-state lighting, leading to new and innovative devices, e.g., for microdisplays, being the core technology for future augmented reality and visualization, as well as point light sources for optical excitation in communications, imaging, and sensing. This explosion of applications is driven by two main directions: the ability to produce very small GaN LEDs (micro-LEDs and nano-LEDs) with high efficiency and across large areas, in combination with the possibility to merge optoelectronic-grade GaN micro-LEDs with silicon microelectronics in a hybrid approach. GaN LED technology is now even spreading into the realm of display technology, which has been occupied by organic LEDs and liquid crystal displays for decades. In this review, the technological transition toward GaN micro- and nanodevices beyond lighting is discussed including an up-to-date overview on the state of the art.

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Structural Modifications in Free-Standing InGaN/GaN LEDs after Femtosecond Laser Lift-Off

Cited by 4 publications

References 6 publications

Ultrashort Pulse Laser Lift-Off Processing of InGaN/GaN Light-Emitting Diode Chips

Ultrashort Pulse Laser Lift-Off Processing of InGaN/GaN Light-Emitting Diode Chips

67‐3: Numerical Simulation for GaN‐based MicroLED Laser Induced Forward Transfer (LIFT) and Comparison With Real‐Time Measurements of the Flight Phase

Beyond solid-state lighting: Miniaturization, hybrid integration, and applications of GaN nano- and micro-LEDs

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