Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 54: Optical Properties

HL 54.6: Talk

Wednesday, March 28, 2012, 12:15–12:30, EW 203

Near-infrared Photoluminescence of Nanostructured Graphite — •Markus Glaser, Rupert Langegger, Alois Lugstein, and Emmerich Bertagnolli — Vienna University of Technology, Institute of Solid State Electronics, Vienna, Austria

The recent research on graphene and its unique physical properties led to the emergence of a new field of technology, called graphene electronics, with possible applications in transistors or optoelectronic devices. As graphene is a single layer of a graphite crystal, the research on graphene also brought the complex physical properties of graphite back into the center of attention. Recently we presented a method for extracting graphite sheets of varying thickness on bulk HOPG by focused ion beam processing at elevated sample temperatures. These graphite sheets were found to exhibit a distinct near-infrared photoluminescence (PL) signal at 532 nm laser excitation. Further investigation of this unexpected PL was done on several synthetic and natural graphite samples that were mechanically exfoliated with a scotch tape and deposited on silicon substrates with an isolating sacrificial layer. The PL signal is found to be stable at cw laser excitation with power densities of about 400 kW/cm² to tens of MW/cm² where no destruction of the sample flakes was observed. A possible dependence of PL on the flake thickness and its lateral dimensions is proposed. Furthermore we assume that crystalline graphite is essential for the PL, which was verified by Raman spectroscopy. Electrical characterization and photocurrent measurements where done to determine a possible application in optoelectronic devices.