NO2 gas sensing with Au/phthalocyanine/Si heterostructures

The current-voltage characteristics of the heterostructure cell of Au/vanad ylphthalocyanine (VOPc) layers/Si were investigated in NO2 atmosphere. The cells showed a rectification behavior and an increase in current at the pre sence of NO2 gas. The NO2 gas was detected even for the Au/Si cell without VOPc layers and the sensitivity was found to be enhanced significantly by i nsertion of VOPc layers. The cell with 10 nm-thick VOPc layers exhibited an increase in current density by a factor of 15 in 6 ppm NO2 atmospher It wa s thus suggested that the interface between Au/Si and VOPc/Si play a key ro le to determine the gas sensing properties. The adsorbed NO2 gas molecules are thought to modify the interface potential.