Structure of phthalocyanine overlayers on the [formula omitted] surfaces of InSb and InAs

Abstract

The structure of free-base phthalocyanine (H 2Pc) and copper phthalocyanine (CuPc) overlayers deposited on the indium-terminated InSb(1 0 0) and InAs(1 0 0) (4×2)/c(8×2) reconstructed surfaces have been studied by low-energy electron diffraction and van der Waals (vdW) intermolecular interaction energy calculations. The diffraction pattern for H 2Pc grown on InSb(1 0 0) is a superposition of a (3×3) and (√10×√10) R±18.4° structure, whilst no ordered structure is formed when H 2Pc is grown on InAs(1 0 0). In contrast, CuPc films exhibit a (3×3) structure on InSb(1 0 0) and a (√10×√10) R±18.4° structure on InAs(1 0 0). These differences can be rationalised by the vdW intermolecular interaction energy calculations of the quadratic unit cells of H 2Pc and CuPc. The results show that the lattice structure during the initial stages of thin film growth is influenced strongly by the intermolecular interaction energy of their unit cells.