Fluctuation and commensurability effect of exciton density wave

© 1995-2012 IEEE. We present the first reliability study of InAs/GaAs self-assembled quantum dot lasers epitaxially grown on Ge/Si substrates. Some devices maintain lasing oscillation after more than 2700 h of constant current stress at 30 °C, longer than any previous life tests of GaAs lasers epitaxially grown on silicon. No catastrophic failures were observed. The lasers were characterized to gain insight on the aging mechanism. Copyright Information: All rights reserved unless otherwise indicated. Contact the author or original publisher for any necessary permissions. eScholarship is not the copyright owner for deposited works. Learn more at http://www.escholarship.org/help_copyright.html#reuse PHYSICAL REVIEW B 91, 245302 (2015) Fluctuation and commensurability effect of exciton density wave Sen Yang,1 L. V. Butov,1 B. D. Simons,2 K. L. Campman,3 and A. C. Gossard3 1Department of Physics, University of California at San Diego, La Jolla, California 92093-0319, USA 2Cavendish Laboratory, Madingley Road, Cambridge CB3 OHE, United Kingdom 3Materials Department, University of California at Santa Barbara, Santa Barbara, California 93106-5050, USA (Received 27 January 2015; revised manuscript received 8 May 2015; published 3 June 2015) At low temperatures, indirect excitons formed at the in-plane electron-hole interface in a coupled-quantum-well structure undergo a spontaneous transition into a spatially modulated state. We report on the control of the instability wavelength, measurement of the dynamics of the exciton emission pattern, and observation of the fluctuation and commensurability effect of the exciton density wave. We found that fluctuations are suppressed when the instability wavelength is commensurate with defect separation along the exciton density wave. The commensurability effect is also found in numerical simulations within the model describing the exciton density wave in terms of an instability due to stimulated processes. DOI: 10.1103/PhysRevB.91.245302 PACS number(s): 78.67.De, 71.35.Lk, 78.55.Cr, 89.75.Kd