Electrical characterization of self-assembled monolayers of alkyltrichlorosilanes on native oxide of silicon.

The octadecyltrichlorosilane (C18), dodecyltrichlorosilane (C12) and octyltrichlorosilane (C8) monolayers have been deposited on the native oxide of silicon by self-assembly technique. The morphology of the monolayers studied by atomic force microscopy revealed an average roughness of approximately 1.0 A. The Fourier Transform Infra Red Spectroscopic measurements revealed the presence of peaks at approximately 2848 and 2915 cm(-1) indicating the formation of densely packed monolayers. The current density versus voltage (J-V) measurements using mercury drop as counter electrode showed tunneling current between 10(-5) to 10(-8) A/cm2 at 1 V indicating the excellent dielectric behaviour of these monolayers. The J-V data were fitted to Simmons theory of tunneling which yielded an effective electron energy barrier height of 1.6 +/- 0.2 eV and the effective mass of electron tunneling through the barrier was found to be 0.3 +/- 0.03 m(e). The tunneling decay factor beta was estimated from the current density values measured as a function of thickness of the monolayer and was found to be 0.28 +/- 0.02 A(-1).