Abstract :
Copper phthalocyanine thin ®lms were prepared by vacuum deposition at various substrate temperatures onto glass and
gold. The effects of substrate temperature and material on ®lm morphology and crystalline structure were studied, and the ®lm
characteristics were related to their gas-sensing properties for NO2. We ®nd that CuPc ®lms have ®ne-grain morphology and
small degree of crystallization at low substrate temperature (Td 28 C). When Td is elevated to 1008C, ®ber-like morphology
was observed on both substrates, with orientation mainly parallel to the substrate. At 150±2008C, the ®bers grow larger
without signi®cant change of orientation on glass, but whisker structures with less order were formed on gold. The ®ber-like
structure prepared at 1008C has the highest electrical conductivity, which also implies that the stacking axis of the Pc
macrocycle is the high conductivity direction. This characteristic also leads to quick response and higher sensitivity of this
®lm to NO2. The effects of substrate temperature on the ®lm characteristics and gas-sensing properties are compared to the
heat-annealing effects observed in our previous work. # 2001 Elsevier Science B.V. All rights reserved
