Paper EM+TF-WeM4
Probing the Intrinsic Organic/Semiconductor Interface

Wednesday, October 31, 2012, 9:00 am, Room 009

The electronic properties of organic/semiconductor interfaces are crucial for a variety of applications, such as organic dielectrics and organic/inorganic hybrid solar cells. However, the accurate characterization of these interfaces is prevented by the large tunneling current through the molecular layer. Moreover, standard fabrication methods, such as the formation of top metal contact via evaporation, cause damages during the processing even if applied directly with extreme caution. We present here a novel method to protect the interface with a layer of high-κ dielectric (Al₂O₃) gently deposited on top of the organic layer using atomic layer deposition. The metal precursor reacts with the carboxylic head group of the self-assembled monolayer (SAM) layer without affecting the underlying SAM/Si interface. Due to the increase of the dielectric layer thickness (SAM+Al₂O₃), a large reduction in tunneling leakage current occurs, and conductance voltage measurements can be implemented with a mercury probe setup. Moreover, the gate stack shows enough robustness to survive the entire MOS capacitor fabrication. Capacitance voltage measurements show small frequency dispersion and a low D_it, on the order of 10¹¹ cm^-2eV^-1, for the intrinsic SAM/Si interface demonstrating inherent high quality when it is protected by the Al₂O₃ layer.