Pulsed plasma polymerized dichlorotetramethyldisiloxane high-k gate dielectrics for polymer field-effect transistors

摘要

Polymerized dichlorotetramethyldisiloxane (DCTMDS) films deposited by radio-frequency pulsed plasma polymerization (PPP) demonstrated very high dielectric constants for a polymer-based system, in the range of 7-10. The high dielectric constants of PPP DCTMDS films are due to the high polarizability of the DCTMDS monomer. The pulsed plasma duty cycle (on/off) resulted in slightly higher dielectric constant DCTMDS films for higher duty cycles. The variation of dielectric constants does not show any trend with varying film thicknesses, indicating that the thickness of the deposited films is not significant for controlling permittivity. Postdeposition annealing in a certain temperature range improves the electrical integrity of PPP DCTMDS films, but temperatures that are too high induce even higher leakage than the samples with no heat treatment. An optimal annealing temperature was identified to be in the range of 150-200℃. Samples annealed within this temperature window have low leakage current densities below 0.1 pA/μm~2 at 10 V for film thicknesses about 100 nm. Poly(3-hexythiophene) polymer field-effect transistors (PFETs) using PPP DCTMDS gate dielectric films were fabricated and tested. Due to the high dielectric constants of PPP DCTMDS, these PFETs possess high gate capacitance and operate at low voltage.