|Title:||Latest Results of Nitride-based Nonpolar/Semipolar LEDs and Laser Diodes|
|Group/Series/Folder:||Record Group 8.15 - Institute for Advanced Study|
Series 3 - Audio-visual Materials
|Notes:||IAS Distinguished Lecture.|
Title from slide title.
Abstract: All of commercially available blue, green & white LEDs and blue laser diodes use c-plain (polar) GaN. Prof Nakamura and his group has developed nonpolar/semipolar GaN devices to create high efficient LEDs and laser diodes with an advantage of much smaller piezoelectric field and non- isotropic strain to change the valance band energy structure. As a result, the high efficient nonpolar/ semipolar blue, green LEDs and blue&green laser diodes have been achieved. Among many kinds of semipolar LEDs, interesting characteristics of (20-2-1) semipolar LEDs were found. The efficiency droop of (20-2-1) semipolar blue LEDs with an external quantum efficiency of about 50% was very small at a current density of up to 400A/cm2. The spectrum width of (20-2-1) LEDs was much narrower than that of conventional c-pain and other semipolar/nonpolar LEDs. The blue-shift of the peak emission wavelength of (20-2-1) LEDs with increasing the forward current was almost negligible in comparison with that of the conventional c-plain or other semipolar/nonpolar LEDs. These results suggest that InGaN layer of the semipolar (20-2-1) plain is homogeneous. The latest results of those devices and material growth are described including bulk GaN crystal growth using the Ammonothermal method.
Prof Shuji Nakamura obtained his bachelor’s and master’s degrees in electronic engineering in 1977 and 1979 respectively, after which he joined the Nichia Corporation in Japan. It was while working for Nichia that Prof Nakamura invented the first high brightness GaN LED whose brilliant blue light is (when partially converted to yellow by a phosphor coating) the key to white LED lighting, and which went into production in 1993. He was awarded a Doctor of Engineering degree by the University of Tokushima in 1994. He left Nichia Corporation in 1999 and joined the University of California at Santa Barbara. Widely recognized as pioneer in light emitters based on wide-bandgap semiconductors, Prof Nakamura continues to focus on development of GaN thin film technology. He won the 2006 Millennium Technology Prize for his invention of blue and white LEDs. He was elected as a member of the US National Academy of Engineering in 2003. He holds more than 100 patents and has published more than 400 papers in his field.
Duration: 54 min.
|Appears in Series:||8.15:3 - Audio-visual Materials|
Videos for Public -- Distinguished Lectures