Effects of laser sources on the reverse-bias leakages of laser lift-off GaN-based light-emitting diodes

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

doi:10.1063/1.2749866

Cited by 59 publications

(47 citation statements)

References 10 publications

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“…However, in the case of the LLO process, there is a problem to decompose the GaN into liquid gallium and gaseous nitrogen [3,4]. Moreover, there is local heating over the critical sublimation temperature of gallium, the LLO process inevitably causes a considerable degradation of GaN [5]. Recently, Ha et al [1] reported new method for fabricating vertical LED by using the chemical lift-off (CLO) process.…”

Section: Introductionmentioning

confidence: 98%

Hydride vapor phase epitaxy of GaN on the vicinal c-sapphire with a CrN interlayer

Lee

et al. 2009

Journal of Crystal Growth

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Section: Introductionmentioning

confidence: 98%

Hydride vapor phase epitaxy of GaN on the vicinal c-sapphire with a CrN interlayer

Lee

et al. 2009

Journal of Crystal Growth

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“…This fact manifests that the atomic movements needed for the observed dislocation generation and MQW intermixing are mainly due to the combined effects of REDR and the phonon generation as the generated electrons and holes move to their relevant band edges to recombine, while many people have argued that the generation and propagation of shock wave at/from the GaN/Al 2 O 3 interface would be the main origin of the increase of the dislocations in the bottom GaN layer after the LLO process. [5][6][7] This reasoning can also explain how the QW intermixing may be so apparent even with a rather small number of the KrF photons arriving at the MQWs (1.5 × 10 16 /cm 2 ). The difference between the KrF photon energy and the bandgap energy of GaN (In 0.3 Ga 0.7 N) is 1.6 (2.2) eV.…”

Section: Fig 5 (A)mentioning

confidence: 99%

“…5 The screw dislocations generated by the LLO process are believed to lead to an increase in the leakage current in the vertical LEDs. 6 Even though many studies have been reported on the damage effect of the LLO process on the GaN layers, 5-9 few works have been reported on the effects of the LLO process on the InGaN/GaN multiple quantum well (MQW) layers of the GaN-based LEDs. And most of the reported optical studies have been performed by using photoluminescence (PL) characteristics.…”

Section: Introductionmentioning

confidence: 99%

“…2 Recently, many works have been reported on the vertical InGaN/GaN LED structure for which the sapphire substrate is removed using a laser lift-off (LLO) technique and carrier materials such as Cu or Si are employed on top of the LEDs for the LLO process. [4][5][6][7][8] The resulting vertical LEDs show an improved high current operation capability than conventional LEDs. 4 However, a high power KrF UV laser which is usually employed for the LLO process is known to affect the material properties of the InGaN/GaN LED structures.…”

Section: Introductionmentioning

confidence: 99%

“…4 However, a high power KrF UV laser which is usually employed for the LLO process is known to affect the material properties of the InGaN/GaN LED structures. [5][6][7][8] Chen et al have reported that, in addition to the superficial damage caused by KrF laser absorption, the shock waves can generate a cluster of half loops above the LLO interface. 5 The screw dislocations generated by the LLO process are believed to lead to an increase in the leakage current in the vertical LEDs.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Influence of laser lift-off on optical and structural properties of InGaN/GaN vertical blue light emitting diodes

et al. 2012

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The influences of the laser lift-off (LLO) process on the InGaN/GaN blue light emitting diode (LED) structures, grown on sapphire substrates by low-pressure metalorganic chemical vapor deposition, have been comprehensively investigated. The vertical LED structures on Cu carriers are fabricated using electroplating, LLO, and inductively coupled plasma etching processes sequentially. A detailed study is performed on the variation of defect concentration and optical properties, before and after the LLO process, employing high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM) observations, cathodoluminescence (CL), photoluminescence (PL), and high-resolution X-ray diffraction (HRXRD) measurements. The SEM observations on the distribution of dislocations after the LLO show well that even the GaN layer near to the multiple quantum wells (MQWs) is damaged. The CL measurements reveal that the peak energy of the InGaN/GaN MQW emission exhibits a blue-shift after the LLO process in addition to a reduced intensity. These behaviors are attributed to a diffusion of indium through the defects created by the LLO and creation of non-radiative recombination centers. The observed phenomena thus suggest that the MQWs, the active region of the InGaN/GaN light emitting diodes, may be damaged by the LLO process when thickness of the GaN layer below the MQW is made to be 5 μm, a conventional thickness. The CL images on the boundary between the KrF irradiated and non-irradiated regions suggest that the propagation of the KrF laser beam and an accompanied recombination enhanced defect reaction, rather than the propagation of a thermal shock wave, are the main origin of the damage effects of the LLO process on the InGaN/GaN MQWs and the n-GaN layer as well

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Heterogeneous Integration of Microscale GaN Light‐Emitting Diodes and Their Electrical, Optical, and Thermal Characteristics on Flexible Substrates

Liu

et al. 2017

Adv Materials Technologies

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LEDs that can be utilized as implantable light sources have been playing increasingly important roles in neuroscience research, along with the development of genetically encoded actuators and indicators. [3,4] In particular, gallium nitride (GaN)/indium gallium nitride (InGaN) based blue LEDs are utilized as implantable light sources for optogenetic stimulation and/or exciting fluorophores for neural signal sensing. [5,6] High performance GaN blue LEDs are typically grown on rigid, single crystalline substrates including sapphire, [7,8] silicon (Si) [1] and silicon carbide (SiC), [9] and novel strategies on growing and releasing GaN devices on unusual substrates like zinc dioxide coated graphene, [10] boron nitride (BN), [11] amorphous glasses, [12] nanovoid-mediated substrates, [13] etc. are also actively explored. [14] Although diced bare LED chips have found their uses in wearable and implantable systems by flip-chip bonding, [15,16] thinfilm LEDs (with thicknesses less than 10 µm) with various emission wavelengths that are released from original growth substrates and integrated onto flexible and stretchable substrates are more desirable for biomedical applications. [17] Recent results have successfully demonstrated that released, thinfilm LEDs are integrated with flexible, stretchable, and even biodegradable substrates with better biocompatibilities like improved skin conformance and reduced lesion during implantation. [5,18,19] Thin-film, freestanding red and infrared (IR) LEDs based on gallium arsenide can be easily formed by selective sacrificial etching; [20] however, conventional techniques for thinfilm GaN based purple/blue/green LED release and integration typically rely on sophisticated process steps including laser liftoff (LLO) (for GaN on sapphire), [21,22] chemical etching (for GaN on Si), [1,23,24] wafer bonding, [25][26][27] layer transfer, [11] device pick and place, [28,29] etc., [30,31] thus limiting their use. While GaN LED epitaxial liftoff and integration with flexible substrates have been extensively exploited for various planar device architectures like GaN LEDs on graphene, [7,10] BN, [11] glasses with nanovoids, [12,13] Si, [32] SiC-on-insulator, [9] the performance of these devices is still inferior to their counterparts on conventional sapphire substrates, in terms of their current-voltage characteristics, quantum efficiencies, etc. Therefore, it is highly desirable to develop simple and reliable technologies to implement the mainstream, state-of-the-art GaN LEDs (for example,

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Effects of laser sources on the reverse-bias leakages of laser lift-off GaN-based light-emitting diodes

Cited by 59 publications

References 10 publications

Hydride vapor phase epitaxy of GaN on the vicinal c-sapphire with a CrN interlayer

Hydride vapor phase epitaxy of GaN on the vicinal c-sapphire with a CrN interlayer

Influence of laser lift-off on optical and structural properties of InGaN/GaN vertical blue light emitting diodes

Heterogeneous Integration of Microscale GaN Light‐Emitting Diodes and Their Electrical, Optical, and Thermal Characteristics on Flexible Substrates

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