Effective reduction of bowing in free-standing GaN by N-face regrowth with hydride vapor-phase epitaxy

Chen, Kuei Ming; Huang, Hsin‐Hua; Kuo, Yi Lin; Wu, Pei Lun; Chu, T. L.; Yu, Hung Wei; Lee, Wei I.

doi:10.1016/j.jcrysgro.2009.01.073

Cited by 7 publications

(5 citation statements)

References 20 publications

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“…To minimize these dislocations, there is need for a crystal growth method that reduces bowing. Internally focused laser processing , using a polycrystalline GaN film on the back side of the substrate , and GaN growth on a GaN substrate are effective methods of reducing bowing. Hence, we carried out HVPE growth on GaN substrates.…”

Section: Resultsmentioning

confidence: 99%

Growth of semipolar {20–21} GaN and {20–2–1} GaN for GaN substrate

Hashimoto

Yamane

Okada

et al. 2015

Physica Status Solidi (b)

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In this article, we present a semipolar {20–21} GaN layer and {20–2–1} GaN layer for large GaN substrates. The {20–21} GaN layer was fabricated on {22–43} patterned sapphire substrates (PSSs) by metal‐organic vapor‐phase epitaxy (MOVPE) and hydride vapor‐phase epitaxy (HVPE). We found that the surface roughening and crack generation during the HVPE growth were suppressed by the formation of SiO2‐striped masks parallel to the c‐axis on the MOVPE‐grown {20–21} GaN template. Furthermore, we demonstrated millimeter‐thick crystal growth on a {20–21} GaN layer and a {20–2–1} GaN layer on a GaN substrate using HVPE. The dark‐spot density in the {20–2–1} GaN layer was approximately 9.6 × 106 cm−2 for 960 min growth. The dark‐spot density in the {20–2–1} GaN layer decreased more rapidly than that in the {20–21} GaN layer as growth thickness increased.

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Section: Resultsmentioning

confidence: 99%

Growth of semipolar {20–21} GaN and {20–2–1} GaN for GaN substrate

Hashimoto

Yamane

Okada

et al. 2015

Physica Status Solidi (b)

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“…Note that the bowing is significantly relaxed in the SAG LED structure, whereas it is further increased in the case of the conventional LED (photograph was taken by reversing the sample to show the bowing effect explicitly). The low bowing of the LED structure grown by SAG is most likely due to the suppression of the lateral strain and dislocations 11,16) because of the reduction in lateral dimen-sions, which are difficult to control in conventional growth processes. The top-view images of the LED mesa structures are also shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Furthermore, the difference in thermal expansion coefficient between GaN and sapphire and the growth of strained InGaN on a n-GaN layer lead to severe bowing and bending of LED wafers. 11,12) In addition, when a LED wafer is subjected to LLO, laser irradiation can generate defects, such as dislocations and micro cracks, 13) which can further increase the bowing of GaN LED structures. It is known that strain can affect the optical and electrical characteristics of devices.…”

Section: Introductionmentioning

confidence: 99%

Effect of Ridge Growth on Wafer Bowing and Light Extraction Efficiency of Vertical GaN-Based Light-Emitting Diodes

Ryu¹,

Chandramohan²,

Kim³

et al. 2010

Jpn. J. Appl. Phys.

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In this paper we report on the selective area growth (SAG) of vertical GaN-based light-emitting diodes (LEDs) by low-pressure metal-organic chemical vapor deposition (MOCVD). SAG, under optimized growth conditions, leads to ridge-shaped epilayers with a smooth top surface, devoid of any surface defect structures. The final ridge-shaped vertical LED structures, after the removal of the sapphire substrate by laser lift-off (LLO), exhibit a smaller bowing effect than conventional vertical LED structures. The suppression of lateral strain in the epilayers is responsible for the smaller bowing effect because of the reduction in lateral dimensions. Consequently, the use of SAG LEDs can achieve a 21% higher light output power than conventional vertical LEDs, indicating a significant improvement in light extraction efficiency due to the light guiding pathways offered by the ridge-shaped geometry of the LED structures.

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“…In addition, an inhomogeneous defect distribution along the c-direction of the HVPE-GaN is believed to lead to significant wafer bending. 9) Several approaches have been developed to obtain freestanding GaN wafers with low curvature. [9][10][11][12][13][14] Paskova et al found that GaN layers separated by the laser lift-off (LLO) technique and followed by polishing bent less than those that were self-separated after the HVPE growth process.…”

mentioning

confidence: 99%

“…9) Several approaches have been developed to obtain freestanding GaN wafers with low curvature. [9][10][11][12][13][14] Paskova et al found that GaN layers separated by the laser lift-off (LLO) technique and followed by polishing bent less than those that were self-separated after the HVPE growth process. 10) Geng et al reported that intrinsic straining, which causes wafer bending, could be reduced by the introduction of three-dimensional growth during the initial growth stage of HVPE.…”

mentioning

confidence: 99%

Fabrication of low-curvature 2 in. GaN wafers by Na-flux coalescence growth technique

Imade

Imanishi

Todoroki

et al. 2014

Appl. Phys. Express

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Low-curvature and large-diameter GaN wafers are in high demand for the development of GaN-based electronic devices. Recently, we have proposed the coalescence growth of GaN by the Na-flux method and demonstrated the possibility of enlarging the diameter of high-quality GaN crystals. In the present study, 2 in. GaN wafers with a radius of curvature larger than 100 m were successfully produced by the Na-flux coalescence growth technique. FWHMs of the 002 and 102 GaN X-ray rocking curves were below 30.6 arcsec, and the dislocation density was less than the order of 102 cm−2 for the entire area of the wafer.

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Effective reduction of bowing in free-standing GaN by N-face regrowth with hydride vapor-phase epitaxy

Cited by 7 publications

References 20 publications

Growth of semipolar {20–21} GaN and {20–2–1} GaN for GaN substrate

Growth of semipolar {20–21} GaN and {20–2–1} GaN for GaN substrate

Effect of Ridge Growth on Wafer Bowing and Light Extraction Efficiency of Vertical GaN-Based Light-Emitting Diodes

Fabrication of low-curvature 2 in. GaN wafers by Na-flux coalescence growth technique

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