Direct current electrical characterization of plasma polymerized pyrrole-N,N,3,5 tetramethylaniline bilayer thin films

摘要

The direct current conduction mechanism in plasma polymerized pyrrole-N,N,3,5 tetramethylaniline (PPPy-PPTMA) bilayer thin films has been discussed in this article. A parallel plate capacitively coupled glow discharge reactor was used to deposit PPPy, PPTMA, and PPPy-PPTMA thin films at room temperature onto glass substrates. The Fourier Transform Infrared analyses showed that the PPPy-PPTMA bilayer thin films contained the structural characteristics of both the PPPy and PPTMA. The current density-voltage characteristics of PPPy-PPTMA bilayer thin films of different deposition time-ratios indicated an increase in electrical conductivity as the proportion of PPTMA was increased in the bilayer films. It is also observed that the conductivity of the bilayer thin film is reduced compared with its component thin films. It is seen that in the low voltage region the current conduction obeys Ohm's law, while the charge transport phenomenon appears to be the space charge limited conduction in the higher voltage region. The mobility of the charges, the free charge carrier density, and the permittivity of the PPPy, PPTMA and PPPy-PPTMA bilayer thin films have been calculated. The permittivity for PPPy, PPTMA and PPPy-PPTMA bilayer thin films were found to be 1.07 × 10 ~(-10), 2.2 × 10 ~(-11), and 1.26 × 10 ~(-10) C ~2 N ~(-1) m ~(-2), respectively; the free charge carrier density were (3.56 ± 0.01) × 10 ~(22), 2 × 10 ~(21) and (5.19 ± 0.02) × 10 ~(22) m ~(-3) respectively; and the mobility of the charges were found to be (4.4 ± 0.01) × 10 ~(-19), 1.3 × 10 ~(-13) and (2.1 ± 0.01) × 10 -19 m ~2 V ~(-1) s ~(-1) respectively. PACS: 72.80.Le, 73.21.Ac, 73.40.Rw, 73.50.Gr, 73.61.Ph.