Berlin 2015 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 21: Poster IB (Oxide semiconductors; II-VI and group IV semiconductors; Nanotubes and Buckyballs)

HL 21.29: Poster

Montag, 16. März 2015, 15:00–20:00, Poster B

Transport properties of individual photoluminescent silicon quantum dot studied by scanning tunneling microscopy — •Tuhin Shuvra Basu, Simon Diesch, and Elke Scheer — Fachbereich Physik, Universität Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany.

Silicon quantum dot (Si QD) exhibit room temperature photoluminescence (PL) property due to size induced quantum confinement effects in an ensemble measurement. The ensemble measurement of the PL provides average estimation of their excitonic bandgap and is dependent on size and surface protection [1]. Thus it is important to study the band-structure and exciton dynamics of Si QD on a single particle level. It is expected that the charging energy of Si QD will be appreciably high and will exhibit pronounced single-electron tunneling (SET) effects [2]. By studying tunneling spectroscopy, the conduction and valence band states and their degeneracy can be separately probed. In this work, the electronic transport and bandgap modification of Si QD on a single particle level has been studied by scanning tunneling spectroscopy (STS). The dI/dV curves exhibit features corresponding to the excitonic bandgap. Further the STS study of the individual Si QD by changing the size and the temperature (from 300 mK to 30 K) reveals bandgap fluctuations. We discuss our results in terms of correlations between the exciton dynamics, size, and temperature.

References:

[1]X. Cheng et al., Chem. Soc. Rev. 43, 2680 (2014).

[2]B. Weber et al., Nat. Nanotech. 9, 430 (2014).