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DS: Fachverband Dünne Schichten

DS 45: Organic Thin Films II

DS 45.4: Vortrag

Freitag, 26. März 2010, 12:45–13:00, H8

Bulk-Carrier Analysis in OFETs Utilizing the True Channel Potential. — •Richa Sharma, Benedikt Gburek, Torsten Balster, and Veit Wagner — School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, D-28759, Germany

In an Organic Field Effect Transistor (OFET), it is found that the electrical performance with respect to mobility and on-current increases with thickness. However, as the semiconductor thickness increases, the magnitude of the current in the off state is also found to increase deteriorating the on-off ratio. This is attributed to the increasing bulk current associated with increasing thickness. Therefore, it is crucial to understand the bulk behavior in OFETs at different operating regimes.

For this purpose, potential profiling of OFET channels of different thicknesses is done by 12 sense-fingers patterned in the channel of the transistor. The source, drain and the sense fingers are patterned in one step by optical lithography on the substrate. The semiconductor and insulator are spin-coated from solution and the top-gate is deposited through a shadow mask. The transfer curve measurements along with the potential measurements in the channel are done simultaneously. The corresponding potential profile for a particular gate voltage in the bulk regime is used to obtain the true potential in the channel. This channel potential along with the corresponding bulk current obtained from the transfer curve at different gate voltages is used to analyze the decrease of bulk conductivity in the off regime with increasing gate voltage. A proper model explains the experimental data by carrier depletion of the bulk with increasing gate voltage.