Berlin 2005 – scientific programme
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HL: Halbleiterphysik
HL 24: Bauelemente
HL 24.5: Talk
Saturday, March 5, 2005, 11:45–12:00, TU P-N229
A novel photo-conductive detector for single photon detection — •R. Schmidt1, M. Vitzethum1, S. Malzer1, P. Kailuweit2, D. Reuter2, A. Wieck2, and G.H. Döhler1 — 1Technische Physik I, Universität Erlangen-Nürnberg — 2Angewandte Festkörperphysik, Ruhr-Universität Bochum
We present the concept of an ultra sensitive photo-conducting detector that should be particularly suitable for single-photon detection. It basically represents a p-i-n diode and junction FET integrated into a single device. Extremely high detectivity can be achieved by reducing the electrically active area of the device to the intersection point of two narrow perpendicular doping stripes. Therefore the capacitance of the detector reaches values lower than 0.1 fF, whereas the optical detection area is not reduced. The buried bottom stripe is written by a Focussed ion beam (FIB) directly into GaAs and is then overgrown by the following MBE-layers. The top stripe can be easily defined by wet-chemical etching.
The extremely low capacitance of our device implies charging voltages in the mV-range per photo-generated electron hole pair, leading to a persistent increase in the top-channel current of up to 10 nA. First experimental results show that room temperature dark currents at a few volts reverse bias are in the low pA- and capacitances in the low fF-range. The expected large photo-conductive gain is observed.