Atomic force microscopy work-function difference

It is remarkable that the seeondary electron cut-offs used to determine the work function of all mixtures were sharp and did not show a double step that would refleet two different loeal surface potentials [59], although the films have a nanogranular morphology as determined by atomic force microscopy [27]. Thus, the blends show a eommon vacuum level which shifts linearly with the concentration between the work functions of the neat materials given by d>cuPc 3.8 eV and = 4.3 eV. The linear change of the work function in our studies suggests that CuPe/Cgo mixtures are electronically non-interacting (unless they are optieally exeited). 

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... 

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