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Title: Light harvesting with Ge quantum dots embedded in SiO{sub 2} or Si{sub 3}N{sub 4}

Germanium quantum dots (QDs) embedded in SiO{sub 2} or in Si{sub 3}N{sub 4} have been studied for light harvesting purposes. SiGeO or SiGeN thin films, produced by plasma enhanced chemical vapor deposition, have been annealed up to 850 °C to induce Ge QD precipitation in Si based matrices. By varying the Ge content, the QD diameter can be tuned in the 3–9 nm range in the SiO{sub 2} matrix, or in the 1–2 nm range in the Si{sub 3}N{sub 4} matrix, as measured by transmission electron microscopy. Thus, Si{sub 3}N{sub 4} matrix hosts Ge QDs at higher density and more closely spaced than SiO{sub 2} matrix. Raman spectroscopy revealed a higher threshold for amorphous-to-crystalline transition for Ge QDs embedded in Si{sub 3}N{sub 4} matrix in comparison with those in the SiO{sub 2} host. Light absorption by Ge QDs is shown to be more effective in Si{sub 3}N{sub 4} matrix, due to the optical bandgap (0.9–1.6 eV) being lower than in SiO{sub 2} matrix (1.2–2.2 eV). Significant photoresponse with a large measured internal quantum efficiency has been observed for Ge QDs in Si{sub 3}N{sub 4} matrix when they are used as a sensitive layer in a photodetector device. These data will be presented and discussed, openingmore » new routes for application of Ge QDs in light harvesting devices.« less
Authors:
; ; ; ; ;  [1] ; ;  [2] ; ;  [3] ;  [4]
  1. MATIS IMM-CNR and Dipartimento di Fisica e Astronomia, Università di Catania, via S. Sofia 64, 95123 Catania (Italy)
  2. Department of Physics, Bilkent University, 06800 Ankara (Turkey)
  3. IMM-CNR, VII strada 5, 95121 Catania (Italy)
  4. Department of Physics, Middle East Technical University, 06531 Ankara (Turkey)
Publication Date:
OSTI Identifier:
22275636
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 4; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 77 NANOSCIENCE AND NANOTECHNOLOGY; ABSORPTION; ANNEALING; CHEMICAL VAPOR DEPOSITION; COMPARATIVE EVALUATIONS; GERMANIUM; QUANTUM DOTS; QUANTUM EFFICIENCY; RAMAN SPECTROSCOPY; SILICON NITRIDES; SILICON OXIDES; THIN FILMS; TRANSMISSION ELECTRON MICROSCOPY; VISIBLE RADIATION