Dresden 2003 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 41: Quantenpunkte und -dr
ähte: Optische Eigenschaften II

HL 41.2: Vortrag

Donnerstag, 27. März 2003, 11:15–11:30, POT/81

Studies on few InAs quantum dot micro-LEDs fabricated by focussed ion beam — •R. Fix¹, R. Schmidt¹, M. Vitzethum¹, P. Kailuweit², P. Schafmeister², D. Reuter², A. Wieck², P. Kiesel³, and G.H. Döhler¹ — ¹Technische Physik I, Universität Erlangen-Nuernberg — ²Angewandte Festkörperphysik, Ruhr-Universität Bochum — ³PARC, Palo Alto, CA, USA

We use the high spatial resolution of focussed ion beam implantation (FIB) in order to contact a few (or even single) quantum dots electrically. The active area of our micro-LED is defined by the intersection of two perpendicular doping stripes. The buried stripe is implanted by FIB with either Be⁺ (p-type) or Si⁺ (n-type) ions, and has a nominal width of a few hundred nanometers. This implanted stripe is overgrown by MBE to form an InAs quantum dot layer centered in a 50 nm GaAs layer and a n-(or p-)doped top layer. Using standard photolithography the top layer is patterned to define 1 µm wide stripes. Electroluminescence measurements on micro-LEDs containing an implanted p-stripe reveal the typical spectra of a quantum dot ensemble, but with additional sharp features. These very narrow peaks represent recombination lines of single QD exciton states. Even more encouraging results are expected on new devices with buried FIB-n-doped stripes. This is mainly due to the smaller penetration depth of the Si⁺-ions, resulting in a thinner space charge region and a lower series resistance. Therefore, the carrier injection in n-implanted LEDs should be enhanced significantly.