The cover picture refers to the Rapid Research Letter by Zhiming M. Wang et al.  and displays the nanostructure evolution during GaAs growth by droplet epitaxy. The two colored AFM images of 2 µm × 2 µm show the formation of GaAs nano-crystals shaped like lighted candles and square-holed round coins.
The first author, Zhiming M. Wang, is a research professor at the University of Arkansas, USA, and a member of the Molecular-Beam Epitaxial group of Distinguished Professor Gregory J. Salamo. His current research interests include low-dimensional semiconductor nanostructures, ferroelectronic and ferromagnetic nanostructures, and manipulation of single molecules.
This issue of physica status solidi (a) also contains contributions from the 4th International Conference “Porous Semiconductors – Science and Technology”, held 14–19 March 2004 in Cullera (Valencia), Spain. Further papers from PSST-2004 are published in phys. stat. sol. (c) 2, No. 9 (2005).