Pattern Design of and Epitaxial Growth on Patterned Sapphire Substrates for Highly Efficient GaN-Based LEDs

Lin, Zhien; Yang, Hui; Zhou, Shunhua; Wang, Haiyan; Hong, Xiaosong; Li, Guoqiang

doi:10.1021/cg2016534

Cited by 32 publications

(24 citation statements)

References 29 publications

(30 reference statements)

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“…More importantly, these approaches have no effect on epilayer mode photons. Simulation and experimental results have shown that reducing the pattern size of patterned sapphire substrate (PSS) is effective in improving the LEE by scattering out epilayer mode photons [24,25]. However, small pattern size is disadvantage for crystalline quality of epilayer [26] and the minimal spacing of PSS achieved in practice is far from the best outcoupling spacing for light extraction [27].…”

Section: Introductionmentioning

confidence: 99%

Enhanced Light Extraction of Flip-Chip Mini-LEDs with Prism-Structured Sidewall

Tang

Jia

Liu³

et al. 2019

Nanomaterials

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Current solutions for improving the light extraction efficiency of flip-chip light-emitting diodes (LEDs) mainly focus on relieving the total internal reflection at sapphire/air interface, but such methods hardly affect the epilayer mode photons. We demonstrated that the prism-structured sidewall based on tetramethylammonium hydroxide (TMAH) etching is a cost-effective solution for promoting light extraction efficiency of flip-chip mini-LEDs. The anisotropic TMAH etching created hierarchical prism structure on sidewall of mini-LEDs for coupling out photons into air without deteriorating the electrical property. Prism-structured sidewall effectively improved light output power of mini-LEDs by 10.3%, owing to the scattering out of waveguided light trapped in the gallium nitride (GaN) epilayer.

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Section: Introductionmentioning

confidence: 99%

Enhanced Light Extraction of Flip-Chip Mini-LEDs with Prism-Structured Sidewall

Tang

Jia

Liu³

et al. 2019

Nanomaterials

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“…However, the lattice mismatch between sapphire and GaN is as high as 15%, which leads to a high density of dislocations in LED wafers which reduces the mobility and shortens the lifetime of carriers, and thus decreases the performance of LEDs. 7,8 Many researchers have tried to grow GaN on other materials, such as GaAs, SiC, MgO, MgAl 2 O 4 and ZnO, [9][10][11][12][13] but high-quality epilayers could hardly be obtained because of their relatively large lattice mismatches. 14 Evidently, it is tremendously important to seek a lattice matched substrate for heteroepitaxial growth of high quality GaN-based LED devices.…”

Section: Introductionmentioning

confidence: 99%

Growth and characterization of GaN-based LED wafers on La0.3Sr1.7AlTaO6 substrates

Wang

Yang

2013

J. Mater. Chem. C

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High-quality GaN-based light emitting diode (LED) wafers on La 0.3 Sr 1.7 AlTaO 6 (LSAT) (111) substrates have been demonstrated by molecular beam epitaxy (MBE) for the first time. The structural properties and optoelectronic properties of as-grown LED wafers have been characterized by high-resolution X-ray diffraction (HRXRD), high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), atomic force microscopy (AFM), photoluminescence (PL), and electroluminescence (EL).The small full-width at half-maximum (FWHM) values for both symmetric (0002) and asymmetric (10 12)HRXRD rocking curves indicate that LED wafers on LSAT (111) substrates are of high crystalline quality, the clear and pronounced Pendellösung fringes of XRD from as-grown multiple quantum wells (MQWs)suggest abrupt InGaN/GaN interfaces with designed layer periodicity and the well controlled composition and thickness of each barrier and well layer with the MQWs, which has also been confirmed by HRTEM characterization. The XRD reciprocal space map (RSM) of the (10 15) plane was used to further study the stress state in GaN-based LED wafers. AFM reveals high quality surface morphology for the GaN-based LED wafers on LSAT substrates, with a root-mean-square (RMS) roughness of 1.6 nm. The PL spectrum shows the band edge emission at 445 nm with a FWHM of 24.0 nm. The EL edge emission is observed at 448 nm with a FWHM of 22.6 nm at an injection current of 20 mA, with the light output power of 4.3 mW and the forward voltage of 3.18 V for the chip size of 300 Â 300 mm 2 , indicating good optoelectronic properties of as-grown GaN-based LEDs on LSAT substrates. This achievement reveals the tremendous potential of GaN-based LEDs on LSAT (111) for optoelectronic device applications.

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“…For example, sapphire is widely used as the substrate of a GaN-based light emitting diode (LED) [50][51][52]. Recently, several studies have examined the application of patterned sapphire substrate [53,54]. While the device performance is enhanced significantly by the patterned sapphire, the pattern shapes are still random.…”

Section: Nil Involving Dry Etching Processmentioning

confidence: 99%

Nanoimprint technology for patterning functional materials and its applications

Chen

2015

Microelectronic Engineering

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Pattern Design of and Epitaxial Growth on Patterned Sapphire Substrates for Highly Efficient GaN-Based LEDs

Cited by 32 publications

References 29 publications

Enhanced Light Extraction of Flip-Chip Mini-LEDs with Prism-Structured Sidewall

Enhanced Light Extraction of Flip-Chip Mini-LEDs with Prism-Structured Sidewall

Growth and characterization of GaN-based LED wafers on La0.3Sr1.7AlTaO6 substrates

Nanoimprint technology for patterning functional materials and its applications

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