News from ISCS in San Diego

Nichia Overgrowth Laser

At the 24th International Symposium on Compound Semiconductor in San Diego this week, Shuji Nakamura of Nichia Chemical Industries reported that his new laser structure features lateral overgrowth. This technology was pioneered for GaN by groups at NC State, Santa Barbara and a group in Japan, but has not been previously used in a laser. By controlling the nucleation density artificially, exceptional crystal quality has been reported.

After growing 200Å of GaN on sapphire, a silicon dioxide mask is deposited. Small stripes are etched into the silicon dioxide. The GaN subsequently grown over the silicon dioxide, is virtually defect free.

Nakamura reports 1000 hours of c.w. laser life with the new structure. Presumably, it does help to have defect free material.

UCSB pulsed lasers

On September 5th UCSB graduate students Michael Mack and Amber Abare succeeded in growing, fabricating, and testing an InGaN/GaN laser diode. S. DenBaars reported on some of the following details at the International Symposium on Compound Semiconductors in San Diego on Monday September 8th. Clear TE/TM polarization was observed and a coherent beam emitting a spot in the far field was clearly visible.

UCSB Laser Diode
Jth =23kA/cm²
Pulsed at RT
power output= 17mW
wavelength = 419nm
10 InGaN MQW active reagion
substrate = sapphire
lifetime= over one hour and improving

The program at UCSB was supported by a DARPA grant, Anis Husain program manager.

(9/17/97 Note: the Santa Barbara Group has published their laser results in MRS Internet Journal of Nitride Semiconductor Research , Volume 2, Number 41.)

This report is based on information from M. Yoder and S. DenBaars.