Forced deposition of polar Z-type Langmuir-Blodgett films

Abstract

Polar Z-type Langmuir-Blodgett films have been formed by UV-radiation-induced surface modifications of 10,12-nonacosadiyinoic acid. Metal-insulator-metal (MIM) and metal-insulator-semiconductor (MIS) capacitors were fabricated, tested and compared. Calculated polarization charge densities for the MIM devices were approximately 6.3 × 10 −7 C cm −2. This leads to a molecular dipole moment (assuming the charge separation to be equal to the molecule's length of 3.5 nm) of 9.80 × 10 −28 C cm (2.92 D). A shift in the flat-band voltage of MIS devices due to the built-in polarization field was observed. Using the difference from the flat-band voltage of a non-Z-type MIS capacitor the dipole moment was calculated for comparison with the MIM value. The difference in the dipole moments between the MIM and MIS devices was found to be under 20%.