Spectroscopic Characterisation of Interfaces and Dielectric Layers for OFET Devices

Microscopic and Spectroscopic Characterisation of Interfaces and Dielectric Layers for OFET Devices 

Muller, Y. Burkov, D. Mandal, K. Henkel, I. Paloumpa, A. Goryachko, and D. Schmeifier 

A further spatially resolved method, also based on work function contrast, is scanning Kelvin probe microscopy (SKPM). As an extended version of atomic force microscopy (AFM), additional information on the local surface potential is revealed by a second feedback circuit. The method delivers information depending on the value (p (p(x) + A x). Here, A(zS(x) is the difference in work function between the sample and the AFM tip and cp(x) is the local electric potential [12]. (p x) itself gives information on additional surface charges due to 

The method was introduced by Btirgi et al. for the characterisation of OFETs in the working state with P3HT as the active semiconductor [12]. A continuous variation with an almost constant slope of potential inside the channel region is reported for transistors operating in the linear regime. This behaviour is confirmed by our own measurements, discussed below. 

In addition to lateral information, depth profiling of interface chemistry is important for the understanding of organic functional stractures. X-ray photoelectron spectroscopy (XPS) delivers chemical information for an interface region of around 2 nm in depth. Especially for extended applications, the knowledge of interface reactions, band offsets or charge transfer processes is important. 

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