Condensed Matter Physics Seminar

Professor P.M. Koenraad, Eindhoven University of Technology, the Netherlands

Friday 02 May 2014, 1330-1430
C1 Physics Building

2D and 3D atomic scale analysis of GaSb/GaAs quantum dots

Present day semiconductor nanoscience depends heavily on the precise construction of semiconductor nanostructures in which atomic scale details determine their opto-electronic properties. Amongst others, the team in Tsukuba has shown that droplet epitaxy is a beautiful technique to grown size-controlled and strain free quantum dot nanostructures. It is however of key importance to have novel microscopy techniques that allow assessing the precise atom scale properties, preferable in 3D, in order to fully unravel the growth mechanisms forming these nanostructures and to understand the opto-electronic properties of them.

In this presentation I will show recent results that we have obtained by two exciting microscopy techniques that allow for an atomic scale resolution. We have used cross-sectional Scanning Tunneling Microscopy (X-STM) and Atom Probe Tomography (APT) on a of range semiconductor nanostructures such as quantum dots and rings. The X-STM technique offers a superb 2D true atomic resolution in a single atomic plane intersecting the nanostructure. Atom Probe Tomography is a technique that only recently has become available for the analysis of semiconductor nanostructures. Laser induced field emission is used to get a full, atomically resolved, 3D map of the composition of the semiconductor nanostructure.

In the presentation I will apply and compare these techniques on GaSb/GaAs quantum dots and discuss the challenges and successes with the growth control of these nanostructures.