Atomic force microscopy based room temperature photocurrent‐spectroscopy of single subsurface InAs quantum dots

Abstract

In this work, we present a scheme for room temperature detection of single subsurface InAs quantum dots buried in GaAs by Atomic Force Microscopy based local photocurrent spectroscopy. The measurements were performed at room temperature and ambient conditions. The AFM was used as a nanopositioning system and the AFM tip was used to create a nano‐scale Schottky contact in the vicinity of a QD. The photocurrent spectra clearly showed peaks from quantum dots located in the vicinity of the AFM tip. The spatial resolution of the method was determined to be in between 100 nm and 1000 nm. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

High resolution photocurrent imaging by atomic force microscopy on the example of single buried InAs quantum dots

“…In macroscopic measurements, peaks are broadened due to the size distribution of the QDs in the ensemble, whereas in our measurements of single QDs, the broadening stems from thermal effects only and is in the range of 26 meV. The spectroscopic data are consistent with our previous findings [17].…”

“…This apparent increase in size is explained by the fact that both the eroded area around the QD and the collection region of the AFM tip are larger than the QD itself. It appears that on these samples, the growth conditions were such that the QDs cluster in certain regions [17], and are interconnected by bridge structures. These findings are comparable to the capacitance maps previously recorded on the same sample by our group [20].…”

Photoresponse from single upright-standing ZnO nanorods explored by photoconductive AFM

“…The capability of C-AFM to characterize local photocurrents has already been demonstrated more than a decade ago [32]. Recently, a similar approach of so called PC-AFM has been used to map local photocurrents in different types of solar cells [33–36] and to perform local, AFM-based photocurrent spectroscopy [37–38]. …”

“…In contrast to the first setups where the sample was illuminated through the substrate [32–34 38], we use here a configuration of PC-AFM where the sample is illuminated from the top as already successfully applied to Si and SiGe nanostructures [39–40]. Such a scheme allows us to stay away from any limitations imposed by the substrate.…”