The effect of gate dielectric modification and film deposition temperature on the field effect mobility of copper (II) phthalocyanine thin-film transistors

The change of the field effect mobility of copper (II) phthalocyanine (CuPc) ultra-thin films with the change of dielectric surface and deposition temperature has been systematically investigated. CuPc films are prepared on bare and modified SiO2 substrates at different deposition temperatures. The crystalline structure and morphology of the films have been characterized by x-ray diffraction and atomic force microscopy. The observed device parameters show that the dielectric surface modification reduces the off-state mobile charge carrier density and interfacial trap density. Dielectric surfaces with lower or comparable surface energy to that of CuPc are found to produce devices with higher mobility. The dependence of mobility on deposition temperature shows a strong correlation with the behaviour of the dielectric layers at various temperatures and the diffusion of CuPc molecules.