Materials Systems for 2- to 5-Micrometers Wavelength Diode Lasers
Abstract
Several materials systems are reviewed in attempt to determine the most favorable for use in the fabrication of diode lasers emitting in the 2- to 5-micron wavelength range. Eight possible systems, along with several of their variations, are identified among the III-V, IV-VI, and II-VI semiconductors. All meet the following criteria: optical and carrier confinement can be obtained, a significant portion of the desired wavelength range can be achieved, and the layers that are required to fabricate a double-heterostructure (DH) laser can be lattice matched to a suitable substrate. The performance of III-V laser devices is limited by Auger recombination and free-carrier absorption. The role of the valence band structure in these effects is of particular importance. The III-V system identified as the most promising is GaInAsSb/AlGaAsSb/GaSb, with the quaternary alloy GaInAsSb for the active layer, the quaternary alloy AlGaAsSb for the cladding layers, and GaSb for the substrate. This system offers substrate availability, a wide range of wavelengths, good metallurgical properties and favorable device physics. In this system, DH lasers emitting at approximately 2.3 micron have been operated CW at room temperature with threshold current densities as low as 1.5 A/sq cm, and differential quantum efficiencies as high as 18 percent per facet have been obtained in pulsed room- temperature operation. According to theoretical projections, the threshold current density of such GaInAsSb/AlGaASSb/GaSb lasers will increase with increasing wavelength because of increased Auger recombination and free-carrier absorption. (r.h.)
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 22, 1990
- Accession Number
- ADA228218
Entities
People
- A. J. Strauss
- J. N. Walpole
- R. C. Williamson
- S. H. Groves
- T. C. Harman
Organizations
- Massachusetts Institute of Technology