Effects of Laser Sources on Damage Mechanisms and Reverse-Bias Leakages of Laser Lift-Off GaN-Based LEDs

Cheng, Ji-Yen; Wu, YewChung Sermon; Peng, Wei; Ouyang, Hao

doi:10.1149/1.3148251

Cited by 28 publications

(33 citation statements)

References 18 publications

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“…Even though LLO is routinely used in LED fabrication, an increase in defect density due to the intense laser irradiation was proven in different studies, mainly affecting the device reverse leakage current . Chen at al.…”

Section: Introductionmentioning

confidence: 99%

Femtosecond Laser Lift‐Off with Sub‐Bandgap Excitation for Production of Free‐Standing GaN Light‐Emitting Diode Chips

et al. 2019

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Laser lift‐off (LLO) is commonly applied to separate functional thin films from the underlying substrate, in particular light‐emitting diodes (LEDs) on a gallium nitride (GaN) basis from sapphire. By transferring the LED layer stack to foreign carriers with tailored characteristics, for example, highly reflective surfaces, the performance of optoelectronic devices can be drastically improved. Conventionally, LLO is conducted with UV laser pulses in the nanosecond regime. When directed to the sapphire side of the wafer, absorption of the pulses in the first GaN layers at the sapphire/GaN interface leads to detachment. In this work, a novel approach towards LLO based on femtosecond pulses at 520 nm wavelength is demonstrated for the first time. Despite relying on two‐photon absorption with sub‐bandgap excitation, the ultrashort pulse widths may reduce structural damage in comparison to conventional LLO. Based on a detailed study of the laser impact as a function of process parameters, a two‐step process scheme is developed to create freestanding InGaN/GaN LED chips with up to 1.2 mm edge length and ≈5 μm thickness. The detached chips are assessed by scanning electron microscopy and cathodoluminescence, revealing similar emission properties before and after LLO.

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Section: Introductionmentioning

confidence: 99%

Femtosecond Laser Lift‐Off with Sub‐Bandgap Excitation for Production of Free‐Standing GaN Light‐Emitting Diode Chips

et al. 2019

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“…The substrates are fabricated by utilizing wafer bonding (or electroplating) and LLO methods [11–15]. After sapphire substrate has been removed from the GaN epitaxial layer, the exposed GaN surface is roughened by chemical etching using dilute aqueous KOH to improve its light extraction efficiency [16–20].…”

Section: Introductionmentioning

confidence: 99%

Nanorods on surface of GaN-based thin-film LEDs deposited by post-annealing after photo-assisted chemical etching

2017

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This study investigates the optoelectronic characteristics of gallium nitride (GaN)-based thin-film light-emitting diodes (TF-LEDs) that are formed by a two-step transfer process that involves wet etching and post-annealing. In the two-step transfer process, GaN LEDs were stripped from sapphire substrates by the laser lift-off (LLO) method using a KrF laser and then transferred onto ceramic substrates. Ga-K nanorods were formed on the surface of the GaN-based TF-LEDs following photo-assisted chemical etching and photo-enhanced post-annealing at 100 °C for 1 min. As a result, the light output power of GaN-based TF-LEDs with wet etching and post-annealing was over 72% more than that of LEDs that did not undergo these treatments.

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“…On the other hand, the release of GaN-based epitaxy grown on dissimilar substrate, such as sapphire (-Al 2 O 3 ), involved physical lift-off based on laser lift-off [6][7][8][9], and recently by mechanical lift-off using sacrificial nanoporous GaN [10], and BN [11]. In chemical lift-off process demonstration, the GaN-based epitaxial layers were grown on sacrificial layers, such as ZnO [12], CrN [13], and nanostructured SiO 2 [14], for subsequent chemical etching; alternately Pt-assisted UV electroless chemical etching epitaxial release are employed based on bandgap selective, defect selective, or dopant selective mechanisms [15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

GaN Nano-membrane for Optoelectronic and Electronic Device Applications

Ooi

ElAfandy

Slimane

et al. 2014

Asia Communications and Photonics Conference 2014

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Effects of Laser Sources on Damage Mechanisms and Reverse-Bias Leakages of Laser Lift-Off GaN-Based LEDs

Cited by 28 publications

References 18 publications

Femtosecond Laser Lift‐Off with Sub‐Bandgap Excitation for Production of Free‐Standing GaN Light‐Emitting Diode Chips

Femtosecond Laser Lift‐Off with Sub‐Bandgap Excitation for Production of Free‐Standing GaN Light‐Emitting Diode Chips

Nanorods on surface of GaN-based thin-film LEDs deposited by post-annealing after photo-assisted chemical etching

GaN Nano-membrane for Optoelectronic and Electronic Device Applications

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