Regensburg 2016 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 71: Quantum Dots and Wires: Optical Properties

HL 71.7: Vortrag

Donnerstag, 10. März 2016, 11:30–11:45, H15

Optical investigation of surface Fermi level-pinning in high-periodicity InGaAs nanowire arrays — •Maximilian Sonner, Maximilian Speckbacher, Julian Treu, Stefanie Mörkötter, Kai Saller, Hubert Riedl, Gerhard Abstreiter, Jonathan Finley, and Gregor Koblmüller — Walter Schottky Institut and Physik Department, Tu München, Garching, Germany

Optical investigations of surface Fermi level pinning related effects in InGaAs nanowires (NWs), site-selectively grown by molecular beam epitaxy (MBE) directly on Si (111) substrates, were performed using micro-photoluminescence spectroscopy (PL). In particular, we show that due to the large surface to volume ratio high densities of surface states can lead to pronounced Fermi level pinning and non-radiative recombination, limiting the radiative efficiency of the as-grown NWs. To study these effects in more detail, we provide systematic studies of (i) the diameter dependency and (ii) the InGaAs composition by correlating the luminescence properties in as-grown NWs with NWs passivated by hydrofluoric acid. Power- and temperature-dependent studies show two dominating recombination mechanisms present for NW PL emission: spatially indirect recombination via surface states for small diameters and bulk-like, excitonic transition from WZ/ZB stacking faults [1]. Correlating these results with structural analysis and a tuned carrier concentration via doping experiments will allow further new insights. [1] M. Speckbacher, et al., in preparation (2015)