****************************************************

Electrically injected InGaN/GaN-based DFB laser

Daniel Hofstetter, Robert L. Thornton, Linda T. Romano, David P. Bour
Michael Kneissl, Rose M. Donaldson, and Clarence Dunnrowicz
XEROX Palo Alto Research Center
3333 Coyote Hill Road
Palo Alto, CA 94304

May 13, 1998


XEROX demonstrates the world's first electrically injected nitride-based DFB
laser


We demonstrate room temperature pulsed operation of an electrically injected
InGaN/GaN-based distributed feedback (DFB) laser with an emission wavelength
of 403 nm (0.05 percent duty cycle, 500 ns pulses). The threshold current of
a 1 mm long and 10 micron wide device was 1.6 A; corresponding to a
threshold current density of 16 kA/cm2. A characteristic temperature of T0 =
100 K was measured. The 3rd order grating providing feedback was defined
holographically and dry-etched into the upper waveguiding layer by
chemically-assisted ion beam etching. Epitaxial over-growth of the upper
AlGaN cladding and a GaN contact layer completed the device structure. We
observed single mode operation of the laser with a sidemode suppression
ratio of 15 dB over a temperature range of about 30 K. Changing the
heat-sink temperature allowed us to continuously tune the primary emission
peak of the DFB laser at a rate of 0.14 angstrom/K. This is the first
demonstration of a semiconductor-based DFB laser diode in this spectral
region and in this material system.

This work was partially funded by DARPA (contract # MDA 972-96-3-0014) and
by the Swiss National Science Foundation. Details of this work will be
presented at the IEEE Device Research Conference in Charlottesville, VA
(June 22 - 24, 1998) and in Applied Physics Letters.


****************************************
Daniel Hofstetter
Electronic Materials Laboratory
XEROX Palo Alto Research Center
3333 Coyote Hill Road
Palo Alto, CA 94304

Phone : (650) 812 4136
FAX   : (650) 812 4105
e-mail: hofstetter@parc.xerox.com
****************************************