Berlin 2008 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 23: Quantum dots and wires: Transport properties I
HL 23.7: Vortrag
Dienstag, 26. Februar 2008, 12:30–12:45, EW 201
Franz-Keldysh effect in GaN nanowires — •Raffaella Calarco1, Toma Stoica1, Ralph Meijers1, Thomas Richter1, Anna Cavallini2, Laura Polenta2, Marco Rossi2, and Hans Lüth1 — 1Institute of Bio- and Nanosystems (IBN1) and cni - Center of Nanoelectronic Systems for Information Technology, Research Centre Jülich, 52425 Jülich, Germany — 2Phys.Department and CNISM, University of Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
In recent years III-nitride based nanowires have attracted a lot of interest because of their potential applications for nanoelectronic devices [1]. Due to the large surface-to-volume ratio of the wires, the optoelectronic properties as well as growth processes are essentially dependent on the wire diameter. We have studied GaN NWs obtained by catalyst-free radio frequency PAMBE on Si(111) in N-rich conditions [2-4]. Surface Photovoltage Spectroscopy and Spectral Photoconductivity (SPC) measurements have been carried out to analyze the near band-edge absorption in GaN nanowires [5]. A strong diameter dependence of the band absorption tail was found by SPC measurements. The band-edge tailoring and its wire-diameter dependence can be explained by the Franz-Keldysh effect induced by the electric field at the wire surface. The experimental values of the absorption tail are well in agreement with the results obtained by simulating the electric field in a cylindrical model. [1] Y. Huang etal. Science 294, 9, 1313 (2001). [2] R. Calarco et al.Nano Letters 5, 981 (2005). [3] A. Cavallini et al. Nano Letters, 6(7), 1548 (2006). [4] R. Meijers et al. J.Cryst. Growth, 289, 381 (2006) [5] A. Cavallini et al. Nano Letters, 7, 2166 (2007).