Nakamura Inhomogeneous Crystal Project

Shuji Nakamura (Professor of University of California, Santa Barbara)

ERATO(2004-2009)ERATO
Investigation and control of inhomogeneity of nitride semiconductors
Realization of lighting with less environmental load through utilizing highly effective white LEDs

Research Overview
This research focused on "inhomogeneity", a particularity of nitride semiconductors which play a major role in various applications such as blue laser diodes and high-intensity light-emitting diodes. An attempt was made to realize bulk growth of homogeneous perfect crystals, as well as to enhance device characteristics by intentional utilization of inhomogeneity.

Impact of Research Achievements
■ This was a world-leading development, and formed a significant technological trend in the research of nitride semiconductors.
Produced nonpolar and semipolar LEDs with external quantum efficiencies that exceed those of the conventional LEDs. Opened up the path to the production of next-generation LED and laser diode.
■ Realized the world's first nonpolar blue-violet laser diode.
■ Pioneered the path to a practical way to grow bulk GaN crystals by ammonothermal method.
■ Promoted the physical understanding of GaN group materials through the investigation of light-emitting mechanism, etc., and provided a guideline for the design of a wide variety of devices.
■ Established a venture company toward a full-scale practical use of this technology.
■ Size of the global market of the white LED package will be about 840 billion yen (estimated value in 2013).

Semipolar surface green LED
Semipolar surface green LED
Nonpolar blue-violet laser diode
Nonpolar blue-violet laser diode
Transplantation of an own-oral-mucosa cell sheet for ocular pemphigoid
Polar surface, nonpolar surface and semipolar surface of GaN crystal