The Carbonaceous Film Made by Chemical Vapor Deposition of 2, 5-Dimethyl-p-benzoquinone (2)

Abstract

The electrical conductivity, Hall coefficient, carrier density, carrier mobility and optical band-gap of carbonaceous films made by chemical vapor deposition (CVD) of 2, 5-dimethyl-p-benzoquinone between 500 and 1000°C were measured. Based on these results, the electronic properties for the carbonaceous films have been studied, and the following conclusions could be reached.(1) The carbonaceous film shows a higher electrical conductivity, 4.5×10-3 S·cm-1 for film made at 500°C and about 1×103 S·cm-1 for that made at 1000°C, than that of other carbon materials heat treated at the corresponding temperatures.(2) The carbonaceous films deposited below 700°C have a positive Hall coefficient characteristic of a p-type semiconductor, and above 700°C have a negative Hall coefficient of an n-type semiconductor.(3) At low temperatures of CVD below 700°C, the Hall-carrier density of the carbonaceous films increases with CVD temperature while the carriermobility decreases, the change of electrical conductivity being mainly caused by the increment of the Hall-carrier density.(4) At high temperatures of CVD above 700°C, the electron-carrier mobility of the carbonaceous films increases with CVD temperature while the carrier density was nearly unchanged, the change of electrical conductivity being mainly caused by increment of the electron-carrier mobility.(5) The carbonaceous film deposited at 500°C shows an optical band-gap of 0.25 eV and a mobility gap of 0.3 eV.