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Author Hart, John ♦ Hazbun, Ramsey ♦ Gupta, Jay ♦ Kolodzey, James ♦ Adam, Thomas ♦ Kim, Yihwan ♦ Huang, Yi-Chiau ♦ Reznicek, Alexander
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY ♦ ABUNDANCE ♦ CHEMICAL VAPOR DEPOSITION ♦ ENERGY ABSORPTION ♦ FOURIER TRANSFORM SPECTROMETERS ♦ GERMANIUM ALLOYS ♦ ILLUMINANCE ♦ NEUTRON DIFFRACTION ♦ PHOTOCONDUCTIVITY ♦ PHOTOCONDUCTORS ♦ TEMPERATURE DEPENDENCE ♦ TEMPERATURE RANGE 0273-0400 K ♦ TIN ALLOYS ♦ TIN CHLORIDES ♦ X-RAY DIFFRACTION
Abstract Pseudomorphic GeSn layers with Sn atomic percentages between 4.5% and 11.3% were grown by chemical vapor deposition using digermane and SnCl{sub 4} precursors on Ge virtual substrates grown on Si. The layers were characterized by x-ray diffraction rocking curves and reciprocal space maps. Photoconductive devices were fabricated, and the dark current was found to increase with Sn concentration. The responsivity of the photoconductors was measured at a wavelength of 1.55 μm using calibrated laser illumination at room temperature and a maximum value of 2.7 mA/W was measured for a 4.5% Sn device. Moreover, the responsivity for higher Sn concentration was found to increase with decreasing temperature. Spectral photoconductivity was measured using Fourier transform infrared spectroscopy. The photoconductive absorption edge continually increased in wavelength with increasing tin percentage, out to approximately 2.4 μm for an 11.3% Sn device. The direct band gap was extracted using Tauc plots and was fit to a bandgap model accounting for layer strain and Sn concentration. This direct bandgap was attributed to absorption from the heavy-hole band to the conduction band. Higher energy absorption was also observed, which was thought to be likely from absorption in the light-hole band. The band gaps for these alloys were plotted as a function of temperature. These experiments show the promise of GeSn alloys for CMOS compatible short wave infrared detectors.
ISSN 00218979
Educational Use Research
Learning Resource Type Article
Publisher Date 2016-03-07
Publisher Place United States
Journal Journal of Applied Physics
Volume Number 119
Issue Number 9


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