Growth of an ordered crystalline organic heterojunction

The organic vapor phase deposition (OVPD) growth of both PTCDA (3,4,9,10-perylenetetracarboxylic dianhydride) and copper phthalocyanine (CuPc) thick films on an alkali halide substrate with long range crystalline order was demonstrated. Crystal structure was monitored in situ and in real-time with HP-RHEED and ex-situ with X-ray diffraction in the Bragg-Brentano configuration using a Rigaka Cu Ka rotating anode source. Film thickness was measured post-growth using a variable-angle spectroscopic ellipsometer on solvent-cleaned Si substrates. Surface topography was observed using AFM and SEM after coating the surface with 20 A of Au to prevent charging in the SEM. The d-spacings were calculated for each assigned streak location, to index the HP-RHEED patterns. It was observed that a flat surface that accompanies long range film order can be achieved at low growth temperatures on templating substrates.