High resolution LT-STM imaging of PTCDA molecules assembled on an InSb(001) c(8x2) surface

The self-assembling of 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) molecules deposited on an InSb(001) c(8 x 2) surface at sub-monolayer quantities has been investigated at low temperature (77 K) using scanning tunnelling microscopy. Sub-molecular resolution was obtained on PTCDA molecules. The results reveal that individual PTCDA molecules are arranged on the substrate in chains parallel to the [110] crystallographic direction, correlated with characteristic features of the low temperature InSb(001) c(8 x 2) surface electronic structure. A structural model for PTCDA molecules adsorbed on InSb is proposed.