Laser & Optoelectronics Progress, Volume. 49, Issue 7, 70007(2012)
Research Progress of HB-LED Based on Patterned Sapphire Substrate
In order to make high-brightness LED, patterned sapphire substrate (PSS) is adopted. To make PSS, the first step is to make patterned mask on the planar sapphire substrate, and the second step is to copy the pattern of mask onto the sapphire substrate through etching. To make GaN grow on PSS by epitaxial lateral overgrowth and do subsequent processing, HB-LED based on PSS can be fabricated. The dislocation density of GaN on PSS is decreased from 1010 cm-2 to 107 cm-2, compared with the density of GaN on the planar sapphire substrate. The decrease of dislocation density of GaN decreases the number of carrier which vanish through the nonradiative recombination. Therefore, more photons are emitted from the multi-quantum well (MQW), and the internal quantum efficiency of LED is increased. Furthermore, PSS can effectively scatter the beam of light from the MQW, which increases the probability of light in escaping area, so the extraction rate of LED is enhanced. The combination of the enhancement of internal quantum efficiency and extraction rate greatly improves the photoelectrical characteristic of LED.
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Huang Chengqiang, Chen Bo, Li Chaobo, Xia Yang, Wang Minggang, Rao Zhipeng. Research Progress of HB-LED Based on Patterned Sapphire Substrate[J]. Laser & Optoelectronics Progress, 2012, 49(7): 70007
Category: Reviews
Received: Jan. 31, 2012
Accepted: --
Published Online: May. 10, 2012
The Author Email: Chengqiang Huang (huangchengqiang@ime.ac.cn)