Title :
Very low room-temperature threshold current density dots in a well (DWELL) lasers
Author :
Liu, G.T. ; Stintz, A. ; Li, H. ; Newell, T.C. ; Lester, L.F. ; Malloy, K.J.
Author_Institution :
Center for High Technol. Mater., New Mexico Univ., Albuquerque, NM, USA
Abstract :
It has been predicted that the threshold current density of quantum dot lasers should be lower than that of quantum well lasers due to the reduction in the density of states. In particular, efforts have been made in the past few years to reduce the threshold current density of quantum dot lasers on GaAs substrates. A recently developed approach is to put the InAs dots in a strained In0.2Ga0.8As quantum well. This “dots in a well” (DWELL) design not only improves carrier capture by the dots, but also keeps the density of quantum dots high (up to 7×1010 cm-2). Consequently, ground state lasing from a single layer of dots is possible at reasonable cavity lengths. While competition with radiative quantum well transitions was suggested as a concern, quantum well transitions were not observed in previous work or in this study. In this work, comparisons have been made by putting a single layer of InAs quantum dots into three different quantum wells, In0.10Ga0.9As, In0.15Ga0.85As, and In0.2Ga0.8 As. Very low threshold current densities of 40, 26, and 31 A cm -2 have been achieved with InAs dots in the three systems for the 7.8 mm cavity length, cleaved facet lasers
Keywords :
III-V semiconductors; gallium arsenide; indium compounds; quantum well lasers; semiconductor quantum dots; In0.10Ga0.9)As; In0.10Ga0.9As; In0.15Ga0.85As; In0.2Ga0.8As; density of states; quantum well lasers; radiative quantum well transitions; very low room-temperature threshold current density dots; Gallium arsenide; Molecular beam epitaxial growth; Optical waveguides; Quantum dot lasers; Quantum dots; Quantum well lasers; Stationary state; Substrates; Threshold current; US Department of Transportation;
Conference_Titel :
LEOS '99. IEEE Lasers and Electro-Optics Society 1999 12th Annual Meeting
Conference_Location :
San Francisco, CA
Print_ISBN :
0-7803-5634-9
DOI :
10.1109/LEOS.1999.811799