Current transport and the role of barrier inhomogeneities at the high barrier n-InP | poly(pyrrole) interface

A detailed study of current transport at the Schottky-type n-InP \ poly(pyrrole) interface is presented. At room temperature, this interface exhibits an average quality factor of n = 1.02 +/- 0.02, a C-V barrier height of q phi(b)(CV) = 0.78 +/- 0.01 eV, and a surface recombination velocity over two orders-of-magnitude slower than at ideal n-InP metal interfaces. These latter two parameters imply an effective barrier height of 0.9 eV, which is among the highest values ever reported for an n-InP Schottky-type diode. The quality factor increases monotonically with decreasing temperature reaching a value of 1.23 at 98 K. Substantial curvature is also observed in a Richardson plot at reduced temperature. These temperature dependencies can be quantitatively modeled using thermionic emission theory in the presence of barrier inhomogeneities. Standard models, including thermionic emission with image force effects, interfacial layer models with and without surface states, and tunneling, do not adequately explain the temperature dependence of the quality factor and the curvature in the Richardson plot. (C) 1999 American Institute of Physics. [S0021-8979(99)00723-9].