The effect of annealing temperature and film thickness on the phase of pentacene on the p+-Si substrate

This paper investigates the morphology and crystallizationproperties of the two crystalline phases of pentacene grown bythermal evaporation on p$^+$-Si substrates at room temperature bythe methods of atomic force microscopy and x-ray diffraction. Thiskind of substrate induces a thin film phase and a triclinic phasewhich are formed directly onto p$^+$-Si substrates and constitute alayer consisting of faceted grains with a step height betweenterraces of 15.8,{AA} (1,AA=0.1,nm) and 14.9,{AA},respectively. Above the critical thickness of the thin film phase,lamellar structures are found with an increasing fraction with theincrease of the film thickness. When the film thickness is fixed,the fraction of lamellar structures increases with the increase ofannealing temperature. These lamellar structures are identified asthe second phase with a interplanar distance of 14.9,{AA}corresponding to the pentacene triclinic phase. Furthermore, thethin film phase consisting of several micrometre sized uniformlyoriented grains at an annealing temperature of less than80${^circ}$C and a deposition rate of 0.6,{AA}/s is observed.