Regensburg 2016 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 53: Poster II

HL 53.12: Poster

Mittwoch, 9. März 2016, 09:30–13:30, Poster A

Huge thermal shift of the excitonic charging featured energy in self-assembled quantum dots — •Fabian Brinks, Patrick Labud, Andreas Wieck, and Arne Ludwig — Ruhr-Universität Bochum, Lehrstuhl für Angewandte Festkörperphysik

It has been shown that excitons of different charge can be detected in self-assembled InAs quantum dots (QD) by means of capacitance-voltage (C(V)) spectroscopy [1]. Above bandgap illumination of QDs embedded in a Schottky diode induces electron hole-pairs, while eventually the built-in electric field separates them before recombining. Electrons flow to the back-contact and holes get trapped in the quantum dots. Reducing the built-in field by applying forward bias to the diode, electrons tunnel from a highly n-doped back contact into the quantum dots and form excitonic complexes before recombining. The associated tunnel current can be measured by C(V)-spectroscopy and light induced, well resolved charging peaks appear at lower gate voltages than by tunnelling into the single electron s-states.

Rising the temperature, these light induced peaks shift to significantly lower voltages, whereas the non-light induced s-peaks charging voltage basically stays unaltered.

In our presentation we will discuss various possible origins of this effect.

[1] P. Labud et al., Physical Review Letters 112, 46803 (2014).