Improvement of Charge Transfer Between Electrode and Semiconductor by Thin Metal Oxide Insertion

Efficient charge transfer at semiconductor and electrode interface is one of the most crucial issues for the performance of any electronic device. A counter intuitive phenomenon of transfer improvement by insertion of a thin metal oxide film at the semiconductor and electrode interface has gained much attention recently. In this chapter, we will describe our understanding of the mechanism of performance improvement with such insertions based on our surface analytical investigations. We will start by introducing the measurement techniques utilized in our investigations. We will discuss results on the insertion of a thin layer of MoOx between indium tin oxide (ITO) and two well studied organic semiconductors, and demonstrate that the optimum insertion layer thickness is just a few nanometers. We will also illustrate the importance of high vacuum during the deposition of such insertion layers and the impact of exposure on device performance.