scholarly journals Performance of InGaN Light-Emitting Diodes Fabricated on Patterned Sapphire Substrates with Modified Top-Tip Cone Shapes

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Hsu-Hung Hsueh ◽  
Sin-Liang Ou ◽  
Chiao-Yang Cheng ◽  
Dong-Sing Wuu ◽  
Ray-Hua Horng
Keyword(s):  
Light Emitting Diodes ◽  
Substrate Surface ◽  
Light Output ◽  
Chemical Vapor ◽  
Wet Etching ◽  
Light Output Power ◽  
Light Emitting ◽  
Sapphire Substrates ◽  
Patterned Sapphire Substrates

InGaN light-emitting diodes (LEDs) were fabricated on cone-shaped patterned sapphire substrates (PSSs) by using low-pressure metalorganic chemical vapor deposition. To enhance the crystal quality of the GaN epilayer and the optoelectronic performance of the LED device, the top-tip cone shapes of the PSSs were further modified using wet etching. Through the wet etching treatment, some dry-etched induced damage on the substrate surface formed in the PSS fabrication process can be removed to achieve a high epilayer quality. In comparison to the LEDs prepared on the conventional sapphire substrate (CSS) and cone-shaped PSS without wet etching, the LED grown on the cone-shaped PSS by performing wet etching for 3 min exhibited 55% and 10% improvements in the light output power (at 350 mA), respectively. This implies that the modification of cone-shaped PSSs possesses high potential for LED applications.

Patterned Sapphire Substrates for III-Nitride Epitaxial Growth

2018 ◽  
Vol 12 (2) ◽  
pp. 179-186
Author(s):  
Natsuko Omiya ◽  
Hideo Aida ◽  
Yutaka Kimura ◽  
Yuki Kawamata ◽  
Seong-Woo Kim ◽  
...  
Keyword(s):  
Light Intensity ◽  
Internal Quantum Efficiency ◽  
Light Output ◽  
Light Extraction Efficiency ◽  
X Ray Diffraction ◽  
Light Emitting ◽  
Sapphire Substrates ◽  
Calculated Number ◽  
Patterned Sapphire Substrates

GaN-based light emitting diodes (LEDs) were epitaxially grown on patterned sapphire substrates (PSSs) to investigate the effectiveness of PSSs for improving the internal quantum efficiency (IQE) and light extraction efficiency (LEE) of the LEDs. Using X-ray diffraction (XRD) and light output measurements, it was observed that the PSSs improved the crystal quality of the LED films and enhanced the LED light intensity. Based on these experimental results, we discuss whether the enhanced light intensity can be attributed to improvements in the IQE or the LEE. The contribution of the IQE improvement to the light intensity was estimated through a comparison of the calculated light emitting area of the LED chip and the measured light output. As a result, it was revealed that the IQE improvement is not the main cause of the increase in the light intensity, indicating that the PSSs mainly improve the LEE. A comparison of the calculated number of bumps on the PSSs and the measured light output of the LEDs suggests that an increase in the number of bumps could affect the improvement in the LEE.

scholarly journals Effect of Top-Region Area of Flat-Top Pyramid Patterned Sapphire Substrate on the Optoelectronic Performance of GaN-Based Light-Emitting Diodes

2016 ◽  
Vol 2016 ◽  
pp. 1-8
Author(s):  
Hsu-Hung Hsueh ◽  
Sin-Liang Ou ◽  
Yu-Che Peng ◽  
Chiao-Yang Cheng ◽  
Dong-Sing Wuu ◽  
...  
Keyword(s):  
Sapphire Substrate ◽  
Light Emitting Diodes ◽  
Light Extraction ◽  
Light Extraction Efficiency ◽  
X Ray Diffraction ◽  
Patterned Sapphire Substrate ◽  
Light Emitting ◽  
Sapphire Substrates ◽  
Patterned Sapphire Substrates

The flat-top pyramid patterned sapphire substrates (FTP-PSSs) have been prepared for the growth of GaN epilayers and the fabrication of lateral-type light-emitting diodes (LEDs) with an emission wavelength of approximately 470 nm. Three kinds of FTP-PSSs, which were denoted as FTP-PSS-A, FTP-PSS-B, and FTP-PSS-C, respectively, were formed through the sequential wet etching processes. The diameters of circle areas on the top regions of these three FTP-PSSs were 1, 2, and 3 μm, respectively. Based on the X-ray diffraction results, the full-width at half-maximum values of rocking curves at (002) plane for the GaN epilayers grown on conventional sapphire substrate (CSS), FTP-PSS-A, FTP-PSS-B, and FTP-PSS-C were 412, 238, 346, and 357 arcsec, while these values at (102) plane were 593, 327, 352, and 372 arcsec, respectively. The SpeCLED-Ratro simulation results reveal that the LED prepared on FTP-PSS-A has the highest light extraction efficiency than that of the other devices. At an injection current of 350 mA, the output powers of LEDs fabricated on CSS, FTP-PSS-A, FTP-PSS-B, and FTP-PSS-C were 157, 254, 241, and 233 mW, respectively. The results indicate that both the crystal quality of GaN epilayer and the light extraction of LED can be improved via the use of FTP-PSS, especially for the FTP-PSS-A.

scholarly journals Characteristics of InGaN-Based Light-Emitting Diodes on Patterned Sapphire Substrates with Various Pattern Heights

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Sheng-Fu Yu ◽  
Sheng-Po Chang ◽  
Shoou-Jinn Chang ◽  
Ray-Ming Lin ◽  
Hsin-Hung Wu ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Electrical Characteristics ◽  
Light Emitting ◽  
Sapphire Substrates ◽  
Metal Organic ◽  
Electroluminescence Intensity ◽  
Organic Chemical Vapor Deposition ◽  
Patterned Sapphire Substrates

The optical and electrical characteristics of InGaN-based blue light-emitting diodes (LEDs) grown on patterned sapphire substrates (PSSs) with different pattern heights and on planar sapphire by atmospheric-pressure metal-organic chemical vapor deposition were investigated. Compared with planar sapphire, it was found that the LED electroluminescence intensity is significantly enhanced on PSSs with pattern heights of 0.5 (21%), 1.1 (57%), 1.5 (81%), and 1.9 (91%) μm at an injected current of 20 mA. The increased light intensity exhibits the same trend in a TracePro simulation. In addition, it was also found that the level of leakage current depends on the density of V-shape defects, which were measured by scanning electron microscopy.

GaN-Based LEDs on Nano-Patterned Sapphire Substrates

2011 ◽  
Vol 415-417 ◽  
pp. 656-659
Author(s):  
Jing Zhang ◽  
Shiro Sakai
Keyword(s):  
Nanoimprint Lithography ◽  
Light Output ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Sapphire Substrates ◽  
Metal Organic ◽  
Organic Chemical Vapor Deposition ◽  
Patterned Sapphire Substrates

We have successfully fabricated light emitting diodes (LEDs) based on patterned sapphire substrates (PSSs) fabricated by employing nanoimprint lithography (NIL) technique. The nano-patterns were designed as regular triangles consisting of columns, whose diameters and pitches were 100, 150, 200, 250 nm and 200, 300, 400, 500 nm, respectively. 412 nm wavelength LEDs grown by metal organic chemical vapor deposition (MOCVD) method were also demonstrated. The NIL technique and nano-etching by employing RIE were demonstrated in details. The qualities of all LEDs based on PSSs are superior compared with that non-patterned sapphire substrate LED. The experimental results showed that the light output power was increased by using the PSS structure. At a driving current of 20 mA, the light output powers of LEDs based on PSSs with 200, 300, 400 and 500 nm pitches are enhanced by 59%, 79%, 42% and 48%, compared with the conventional LEDs. These results provide promising potential to increase output powers of commercial light-emitting devices.

Enhanced light output power of GaN-based light emitting diodes with overcut sideholes formed by wet etching

2010 ◽  
Vol 54 (5) ◽  
pp. 575-578 ◽  
Author(s):  
Hyun Kyu Kim ◽  
Hyung Gu Kim ◽  
Hee Yun Kim ◽  
Jae Hyoung Ryu ◽  
Ji hye Kang ◽  
...  
Keyword(s):  
Output Power ◽  
Light Emitting Diodes ◽  
Light Output ◽  
Wet Etching ◽  
Light Output Power ◽  
Light Emitting

Improved Light Output Power of GaN-Based Light-Emitting Diodes Using Double Photonic Quasi-Crystal Patterns

2009 ◽  
Vol 30 (11) ◽  
pp. 1152-1154 ◽  
Author(s):  
Hung-Wen Huang ◽  
Chung-Hsiang Lin ◽  
Zhi-Kai Huang ◽  
Kang-Yuan Lee ◽  
Chang-Chin Yu ◽  
...  
Keyword(s):  
Output Power ◽  
Light Emitting Diodes ◽  
Light Output ◽  
Light Output Power ◽  
Light Emitting

scholarly journals Suppressing the Initial Growth of Sidewall GaN by Modifying Micron-Sized Patterned Sapphire Substrate with H3PO4-Based Etchant

Micromachines ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 622 ◽  
Author(s):  
Wen-Yang Hsu ◽  
Yuan-Chi Lian ◽  
Pei-Yu Wu ◽  
Wei-Min Yong ◽  
Jinn-Kong Sheu ◽  
...  
Keyword(s):  
Sapphire Substrate ◽  
Light Emitting Diodes ◽  
Ex Situ ◽  
Initial Growth ◽  
Patterned Sapphire Substrate ◽  
Light Emitting ◽  
Sapphire Substrates ◽  
Patterned Sapphire Substrates

Micron-sized patterned sapphire substrates (PSS) are used to improve the performance of GaN-based light-emitting diodes (LEDs). However, the growth of GaN is initiated not only from the bottom c-plane but also from the sidewall of the micron-sized patterns. Therefore, the coalescence of these GaN crystals creates irregular voids. In this study, two kinds of nucleation layers (NL)—ex-situ AlN NL and in-situ GaN NL—were used, and the growth of sidewall GaN was successfully suppressed in both systems by modifying the micron-sized PSS surface.

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