This article discusses the results obtained from an extensive comparison set up between nine different European laboratories using different two-dimensional ͑2D͒ dopant profiling techniques ͑SCM, SSRM, KPFM, SEM, and electron holography͒. This study was done within the framework of a European project ͑HERCULAS͒, which is focused on the improvement of 2D-profiling tools. Different structures ͑staircase calibration samples, bipolar transistor, junctions͒ were used. By comparing the results for the different techniques, more insight is achieved into their strong and weak points and progress is made for each of these techniques concerning sample preparation, dynamic range, junction delineation, modeling, and quantification. Similar results were achieved for similar techniques. However, when comparing the results achieved with different techniques differences are noted.

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The charge transfer (CT) process in organic semiconductor thin film structures is an important problem for applications such as photoreceptors and light-emitting devices. The operation of a photoreceptor structure is based on a CT process between a donor molecule and an acceptor transport molecule. We have investigated such a structure formed by vacuum-grown thin films of two organic molecules, N,N'-diphenethyl-3,4,9,1O-perylenetetracarboxylic-diimide (DPEP) and N,N'-diphenyl-N,N'-(3-methylphenyl)-1,1 '-biphenyl-4,4'-diamine (TPD), with femtosecond time-resolved photoemission spectroscopy (TR-PES). By measuring the lifetimes of the excited electron states in the mixtures of these molecules we are able to determine the timescale for the electron transfer (ET) between the excited states of the TPD and DPEP molecules. We show that the biexponential ET dynamics consist of a short component of less than 100 fs and a long component of several hundreds fs in length.

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