M. F. Schouten, M. A. J. van Tilburg, V. T. van Lange, W. H. J. Peeters, R. Farina, M. M. Jansen, M. Vettori, E. P. A. M. Bakkers, J. E. M. Haverkort
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引用次数: 0
Abstract
Direct bandgap group IV semiconductors, like strained Ge, GeSn, or hexagonal SiGe, are considered promising for photonic integration on silicon. For group IV semiconductor lasers, it is crucial to understand the carrier cooling efficiency toward the band edges. From a fundamental perspective, a study of carrier cooling within the Γ-valley of direct bandgap group IV semiconductors is particularly interesting since the Fröhlich interaction is expected to be very weak or even absent in these materials due to the nonpolar lattice. Intravalley carrier relaxation within the Γ-valley of a nonpolar semiconductor has not been experimentally accessible before since it has always been overshadowed by intervalley processes between energetically close indirect conduction band minima. Here, we study carrier cooling in direct bandgap hexagonal silicon-germanium (hex-SiGe) nanowires, allowing us to study carrier cooling in an isolated Γ-valley that is sufficiently separated from the indirect minima. We obtain a hot carrier cooling time of 180 ps in the Γ-valley of hex-SiGe. Although the cooling is much slower than in bulk polar group III/V materials due to the absence of Fröhlich interaction, it is comparable to the cooling time in an InGaAs MQW laser structure. We conclude that carrier cooling does not inherently limit hex-SiGe to serve as a laser gain material. This result is an important insight into the field of group IV semiconductor lasers.
期刊介绍:
Applied Physics Letters (APL) features concise, up-to-date reports on significant new findings in applied physics. Emphasizing rapid dissemination of key data and new physical insights, APL offers prompt publication of new experimental and theoretical papers reporting applications of physics phenomena to all branches of science, engineering, and modern technology.
In addition to regular articles, the journal also publishes invited Fast Track, Perspectives, and in-depth Editorials which report on cutting-edge areas in applied physics.
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Fast Track articles are invited original research articles that report results that are particularly novel and important or provide a significant advancement in an emerging field. Because of the urgency and scientific importance of the work, the peer review process is accelerated. If, during the review process, it becomes apparent that the paper does not meet the Fast Track criterion, it is returned to a normal track.