Nakamura Shuji: Current Status and Development of Gallium Nitride Based Light Emitting Devices

At the China International Semiconductor Lighting Exhibition and Forum (CHINA SSL2009), Professor Nakamura Shuji of the University of California, Santa Barbara published a report titled "The Status and Development of GaN-Based Light-Emitting Devices."

At present, the application of non-polar gallium nitride (Nonpolar GaN) on LEDs and LDs has attracted the attention of international industry. The UCSB research team led by Nakamura Shuji has been a global leader in the publication of non-polar GaN blue LEDs. The LED components developed by the team have low loss and long life, which can be applied not only to the next generation of Blu-ray storage, but also to the development of the green LD, which will be applied to the miniature mobile phone projector and laser TV in the future.

Professor Nakamura said in the report that a blue-violet semiconductor laser device using GaN crystals generally utilizes a polar surface called a c-plane in GaN crystals. The non-polar surface refers to a surface perpendicular to the normal direction of the polar surface. The use of a non-polar surface can reduce the piezoelectric field that causes a decrease in luminous efficiency compared to the use of a polar surface. Therefore, it is theoretically possible to improve luminous efficiency (description of a piezoelectric electric field). At the same time, it also has the characteristics of outputting polarized light. By the above advantages, a blue-violet semiconductor laser element using a GaN crystal non-polar surface can be developed, and pulse oscillation can be successfully completed.