Optical and Thermal Performances of (Ga,In)N/GaN Light Emitting Diodes Transferred on a Flexible Tape

Damilano, B.; Lesecq, Marie; Zhou, Di; Frayssinet, Éric; Chenot, Sébastien; Brault, J.; Defrance, N.; Ebongue, A.; Cordier, Y.; Hoel, Virginie

doi:10.1109/lpt.2018.2858000

Cited by 4 publications

(2 citation statements)

References 38 publications

(39 reference statements)

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“…Their performance could be improved not only by optimizing the material quality and epitaxial structure of the InGaN/GaN layers, but also by carefully tailoring the substrate and packaging to enhance the heat management and light output of the device . The latter aspect includes the development of methods to transfer functional InGaN/GaN LED layers after epitaxial growth from the sapphire substrate to different more adequate carriers, for instance, germanium wafers, metal foils, or flexible substrates …”

Section: Introductionmentioning

confidence: 99%

“…[5] The latter aspect includes the development of methods to transfer functional InGaN/GaN LED layers after epitaxial growth from the sapphire substrate to different more adequate carriers, for instance, germanium wafers, [6] metal foils, [7] or flexible substrates. [8,9] Because the fabrication of GaN substrates is complicated and therefore expensive, functional LED films are usually grown by heteroepitaxy on foreign substrates. [10] In commercial production, sapphire is often utilized because this material is readily available and compatible with GaN growth conditions.…”

Section: Introductionmentioning

confidence: 99%

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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%