GaSb-based Nanocomposites as IR-Emitters
- PDF / 842,978 Bytes
- 4 Pages / 612 x 792 pts (letter) Page_size
- 15 Downloads / 198 Views
E13.34.1
GaSb-based Nanocomposites as IR-Emitters Ludmila Bakueva1, Sergei Musikhin1, Edward H. Sargent1, Stephan Schulz2 1 Department of Electrical and Computer Engineering, University of Toronto, Toronto M5S 3E4, Canada 2 Institut für Anorganische Chemie der Universität Bonn, D-53121, Bonn, Germany ABSTRACT Nanocomposites consisting of GaSb nanocrystals in a conducting polymer matrix were fabricated and investigated. The current-voltage characteristics of the nanocomposite-based diode structures have a symmetric but strongly nonlinear character. Capacitance-voltage characteristics of the structures were investigated both in the dark and under illumination and compared with those of a pure polymer. At applied voltages exceeding 7-10 V (for different samples) electroluminescence begins and steeply increases. The position of the maximum of the measured electroluminescence spectra can be made to vary in the 1.3 - 1.6 µm wavelengths region by changing nanocrystal size. Photoluminescence spectra have a maximum nearly coinciding with that of electroluminescence but of considerably larger width. The results demonstrate the promise of GaSb-based nanocomposites for infrared light-emitting devices operating in the 1.3-1.6 µm spectral region used in optical communication systems. SAMPLE PREPARATION GaSb nanocrystals were fabricated by a temperature-controlled synthesis [6] in solution using Sb(SiMe3)3 prepared as per [6], used in combination with commercially available GaCl3. The solvents were carefully dried, distilled, and degassed prior to use. 2 mmol GaCl3 was dissolved in 50 mL di(isopropyl)benzene and cooled to –50oC. To this solution, 2 mmol Sb(SiMe3)3 was dropwise added via syringe, immediately followed by formation of a white solid.
Figure 1. TEM image of GaSb nanocrystals.
E13.34.2
Slow warming of the mixture to ambient temperature leads to a darkening of both the solid and solution, finally yielding a brown mixture. Heating this mixture to reflux ultimately yields a black solid collected by filtration, washed with pentane, dried in the vacuum and dissolved in toluene for storage, investigation and further processing. TEM observations (Fig.1) revealed that the GaSb phase obtained contained nanocrystals with typical size of order 20 nm, some of which are aggregated in large precipitates. For this reason two different suspensions were used in sample preparation. As polymer matrix materials we used poly[2-methoxy-5-(2-ethylhexyloxy)-1,4phenylenevinylene] (MEH-PPV). Composite samples were prepared by mixing the nanocrystal powder with a polymer precursor, followed by sonication for 1.5 hours and spin coating onto ITO-coated glass and quartz substrates with final annealing for 2 hours in vacuum. The structures for electrical and electroluminescence measurements comprise quartz or glass substrates covered by an ITO (indium-tin oxide) layer used as the anode contact, nanocomposite layers 100-700 nm thick, and upper cathode contacts fabricated by vacuum evaporation of Mg protected from the ambient atmosphere with a thi
Data Loading...
