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 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.

scholarly journals Novel patterned sapphire substrates for enhancing the efficiency of GaN-based light-emitting diodes

RSC Advances ◽  
2020 ◽  
Vol 10 (28) ◽  
pp. 16284-16290 ◽  
Author(s):  
Szu-Han Chao ◽  
Li-Hsien Yeh ◽  
Rudder T. Wu ◽  
Kyoko Kawagishi ◽  
Shih-Chieh Hsu
Keyword(s):  
Silicon Nitride ◽  
Sapphire Substrate ◽  
Light Emitting Diodes ◽  
Patterned Sapphire Substrate ◽  
Light Emitting ◽  
Air Voids ◽  
Sapphire Substrates ◽  
Patterned Sapphire Substrates

A novel patterned sapphire substrate composed of a silicon nitride barrier and air voids was developed for enhancing the efficiency of GaN-based light-emitting diodes.

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.

Improved Light Extraction Efficiency of Light-Emitting Diode Grown on Nanoscale-Silicon-Dioxide-Patterned Sapphire Substrate

2020 ◽  
Vol 12 (5) ◽  
pp. 647-651 ◽  
Author(s):  
Young Hoon Sung ◽  
Jaemin Park ◽  
Eun-Seo Choi ◽  
Hee Chul Lee ◽  
Heon Lee
Keyword(s):  
Silicon Dioxide ◽  
Sapphire Substrate ◽  
Extraction Efficiency ◽  
Light Emitting Diode ◽  
Light Extraction ◽  
Light Extraction Efficiency ◽  
Patterned Sapphire Substrate ◽  
Light Emitting ◽  
Sapphire Wafer ◽  
Luminescence Efficiency

A conical-shaped Si dioxide nano-pattern was employed to sapphire substrate in order to improve the light extraction efficiency of light-emitting diodes. The conical-shaped Si dioxide nano-patterns were fabricated on a 2-inch sapphire wafer using direct imprinting of hydrogen silsesquioxane material. A blue-LED structure was grown on conical-shaped silicon-dioxide nano-patterned sapphire substrates. Photoluminescence and electroluminescence measurements were used to confirm the effectiveness of the nanoscale Si oxide patterned sapphire. An improvement in the luminescence efficiency was observed when nanoscale Si oxide patterned sapphire substrate was used. 1.5 times higher PL intensity and 1.6 times higher EL intensity were observed for GaN LED structure grown on nanoscale Si oxide patterned sapphire, compared to LED structure grown on conventional flat sapphire wafer.

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