Regensburg 2004 – scientific programme

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HL: Halbleiterphysik

HL 37: Quantenpunkte und -drähte: Transporteigenschaften

HL 37.3: Talk

Thursday, March 11, 2004, 10:45–11:00, H13

Direct observation of tunneling escape from InAs/GaAs quantum dots — •Erik Stock, Martin Geller, Roman Sellin, and Dieter Bimberg — Technische Universität Berlin, Institut für Festkörperphysik Hardenbergstr. 35, 10623 Berlin

A major challenge in the investigations of quantum dots (QDs) is to distinguish between two competing charge carrier emission processes: thermal activated and tunneling emission [1]. We report here the first observation of the hole tunneling process via time resolved capacitance transient spectroscopy (DLTS) measurements at low temperature, where thermal emission is negligible. The escape time observed by us is independent from the temperature but strongly depends on the applied reverse bias, which determines the electric field in the QD layer. The measured hole tunneling emission time constant is in the order of seconds (for electric fields of about 100kV/cm), approximately three orders of magnitude larger than for the ground state tunneling of electrons. The dependence of the tunneling time constant on the electric field is compared to a model, assuming a triangular barrier with a potential depth measured directly by DLTS and photoluminescence excitation (PLE) measurements.

This work was funded by the Nanomat project of the European Commission Growth Programme, contract number G5RD-CT-2001-00545, Intas project 2001-774, and SFB 296 of DFG.

[1] C.M.A. Kapteyn et al. Phys. Rev. B 60, (20), 14265 (1999)