The figure depicts a proposed semiconductor laser, based on In(As)Sb quantum dots on a (001) InP substrate, that would operate in the wavelength range between 1.8 and 2.3 μm. InSb and InAsSb are the smallest-bandgap conventional III-V semiconductor materials, and the present proposal is an attempt to exploit the small bandgaps by using InSb and InAsSb nanostructures as mid-infrared emitters.
The most closely related prior III-V semiconductor lasers are based, variously, on strained InGaAs quantum wells and InAs quantum dots on InP substrates. The emission wavelengths of these prior devices are limited to about 2.1 μm because of critical quantum-well thickness limitations for these lattice-mismatched material systems. The major obstacle to realizing the proposed laser is the difficulty of fabricating InSb quantum dots in sufficient density on an InP substrate. This difficulty arises partly because of the weakness of the bond between In and Sb and partly because of the high temperature needed to crack metalorganic precursor compounds during the vapor-phase epitaxy used to grow quantum dots: The mobility of the weakly bound In at the high growth temperature is so high that In adatoms migrate easily on the growth surface, resulting in the formation of large InSb islands at a density, usually less than 5 × 109 cm–2, that is too low for laser operation.
The mobility of the In adatoms could be reduced by introducing As atoms to the growth surface because the In-As bond is about 30 percent stronger than is the In-Sb bond. The fabrication of the proposed laser would include a recently demonstrated process that involves the use of alternative supplies of precursors to separate group-III and group-V species to establish local non-equilibrium process conditions, so that In(As)Sb quantum dots assemble themselves on a (001) InP substrate at a density as high as 4 × 1010 cm–2. Room-temperature photoluminescence spectra of quantum dots formed by this process indicate that they emit at wavelengths from 1.7 to 2.3 μm.
This work was done by Yueming Qiu of Caltech for NASA’s Jet Propulsion Laboratory.
In accordance with Public Law 96-517, the contractor has elected to retain title to this invention. Inquiries concerning rights for its commercial use should be addressed to:
Innovative Technology Assets Management
JPL
Mail Stop 202-233
4800 Oak Grove Drive
Pasadena, CA 91109-8099
(818) 354-2240
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Refer to NPO-40653.
This Brief includes a Technical Support Package (TSP).
Quantum-Dot Laser for Wavelengths of 1.8 To 2.3 µm
(reference NPO-40653) is currently available for download from the TSP library.
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Overview
The document outlines a new technology developed by NASA's Jet Propulsion Laboratory (JPL) concerning a semiconductor quantum-dot laser that operates within the wavelength range of 1.8 to 2.3 microns. This innovation utilizes InSb (Indium Antimonide) quantum dots as the active region, which are self-assembled on a (001) InP (Indium Phosphide) substrate. The primary motivation for this development stems from the limitations of existing InP-based quantum well lasers and InAs (Indium Arsenide) quantum dot lasers, which can only emit light up to 2.1 microns. By employing InSb quantum dots, the new laser technology can achieve longer emission wavelengths, enhancing its potential applications.
The document indicates that while the concept has been developed and some components have been demonstrated, a full prototype has not yet been built, and the invention is not fixed in its final form. The technology is still in the developmental stage, with plans for further research and potential commercialization. Specific applications for this quantum-dot laser include gas sensing and environmental monitoring, which are critical in various fields, including aerospace and environmental science.
The report also notes that there are plans to publish findings related to this technology in journals and present them at conferences, although no disclosures have been made to external parties or through non-disclosure agreements as of the report's date. The technology has not yet been utilized outside of JPL, and there are no current commercial products based on this innovation.
In summary, this document serves as a technical disclosure for a promising quantum-dot laser technology that could significantly impact various applications by providing enhanced performance in the specified wavelength range. The ongoing development and future publications indicate a commitment to advancing this technology for broader use in scientific and commercial markets. The report emphasizes the importance of compliance with export regulations and the proprietary nature of the information contained within.
