IOP PUBLISHING NANOTECHNOLOGY Nanotechnology 18 (2007) 105303 (6pp) doi:10.1088/0957-4484/18/10/105303 Templated growth of 3,4,9,10-perylenetetracarboxylic dianhydride molecules on a nanostructured insulator Jeffrey M Mativetsky, Sarah A Burke, Shawn Fostner and Peter Grutter Department of Physics, McGill University, Montreal, H3A 2T8, Canada E-mail: jeffreym@physics.mcgill.ca Received 12 October 2006, in final form 8 January 2007 Published 6 February 2007 Online at stacks.iop.org/Nano/18/105303 Abstract Nanometre-scale 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) crystallites were produced by trapping the molecules inside monolayer-deep rectangular pits on an alkali halide surface. Noncontact atomic force microscopy was used to measure the crystallite dimensions and lattice structure with molecular resolution. The molecule–substrate lattice mismatch and island heights, typically three to four PTCDA layers, indicate a stress in the first two layers. One- and two-layer crystallites were only observed in pits with side lengths smaller than 10 nm. (Some figures in this article are in colour only in the electronic version) 1. Introduction The prospect of using organic materials as active components in electronic and optoelectronic devices [1, 2] has sparked great interest in the growth of molecular adlayers on solid substrates [3]. Because the structural quality of an organic film plays a critical role in determining its transport properties [4], an understanding of the processes governing the ordering of molecular crystals is of utmost importance. Molecular nanostructures are particularly promising for organic electronics because of the possibility of circumventing the problems imposed by grain boundaries [5], and the potential for interesting size effects. The planar molecule, 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) (figure 1(a)), has long been considered an archetype for organic electronics, because of its extended π -system and its ability to grow in a well ordered fashion on a wide range of substrates [3]. PTCDA typically grows with the molecules lying flat on the substrate surface in a herringbone arrangement (figure 1(b)), forming stacks of two-dimensional sheets which closely correspond to the (102) plane of the two known bulk structures (termed α and β )[6]. Scanning tunnelling microscopy and electron-based surface science techniques have greatly improved our Figure 1. (a) Chemical structure and space-filling model of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), with dimensions. (b) Schematic diagram of the PTCDA (102) plane with unit cell. The two bulk structures, the α-phase and β -phase, differ in their lattice constants as well as in the direction and magnitude of the lateral offset between layers (α-phase: b 1 = 1.196 nm, b 2 = 1.991 nm, offset = 0.190 nm; β -phase: b 1 = 1.245 nm, b 2 = 1.930 nm, offset = 0.195 nm). The directions of the interlayer offsets are indicated. understanding of the growth of PTCDA [7–10] and other molecules [11] on conducting substrates; however, little is known about the growth of molecules on insulators. In the context of organic electronics, an insulating substrate is important for the construction of electrically isolated 0957-4484/07/105303+06$30.00 1 © 2007 IOP Publishing Ltd Printed in the UK