| The electrical properties of several inorganic semiconductor (IS)-doped conjugated polymer (DCP) interfaces are reported in order to address long standing issues regarding both potential barrier formation and the kinetics of charge transport at semiconductor interfaces as well as issues peculiar to the incorporation of a DCP.; The most extensively studied system is the InP-polypyrrole phosphomolybdate hybrid (PMH) interface. Using this system, a rigorous approach is developed both to extract and interpret parameters characterizing the IS-DCP interface, such as the barrier height &phis;b and the transmission coefficient kappa, in light of classic transport anomalies. This approach results in general criteria that must be met to establish confidence in the extracted parameters for the more general class of IS-conductor interfaces that encompasses IS-metal, IS-DCP, and IS-small molecule redox couples.; Using the established criteria, it is demonstrated for InP-PMH interfaces that &phis;b depends on the electrochemical potential of the contact material ( m&d1; PMH), in contrast to strongly Fermi level pinned IS-metal interfaces. It is also demonstrated that kappa can be many orders of magnitude smaller than at IS-metal interfaces, and that it depends on both the relative energy for carrier transport, as well as the doping level of the DCP. Comparisons between InP, GaAs and Si-PMH interfaces are also made to establish the generality of these observations. Although both the Si and GaAs-PMH interfaces exhibit electrical properties that are much less ideal, some approximate conclusions can still be drawn. Contrary to InP-PMH interfaces, which are sensitive to m&d1; PMH and can be controlled over a much wider range than analogous InP-metal interfaces, interfaces between n-Si and PMH are much less sensitive to m&d1; PMH, while complications accompanying manipulation of m&d1; PMH at n-GaAs | PMH precludes this determination. This comparison between InP, Si and GaAs-PMH interfaces suggests that interface structure plays a significant role in determining the electrical properties of the interface. Furthermore, nearly all of the interfaces studied exhibit a reduced value of kappa, as compared to IS-metal interfaces, indicating that the molecular nature of the DCP contact may limit charge transport in a manner analogous to interfaces between IS-small molecule redox couples.; This dissertation includes both my previously published and coauthored materials. |
