Origin of ring defects in high In content green InGaN/GaN MQW: An Ultrasonic Force Microscopy Study
F. Shahedipour-Sandvik, M. Jamil, K.Topol, J. R. Grandusky, Kathleen A Dunn
College of Nanoscale Science and Engineering, University at Albany-SUNY, Albany, NY 12203
J. Ramer, V. N. Merai
Veeco Corp. 394 Elizabeth Avenue, Somerset, NJ 08873
This article was received on Tuesday, June 21, 2005 and
accepted on Monday, October 3, 2005. Abstract
Observation
of GaN-based islands surrounded by V-defects in the barrier layer of green LED
is reported for InGaN MQWs deposited under no hydrogen or at growth
temperatures of less than 800°C. Nanoscale mechanical properties of
the areas enclosed and outside of the ring defects does not show any
appreciable variation as measured by UFM. Chemical etching of the MQW structure
in addition to cross-sectional TEM analysis ruled out the possibility of growth
of inversion domains of N-polar GaN in a Ga-polar GaN matrix. 