SEMICONDUCTOR ANALYSIS USING THE CUPC P-SI AND PTCDI P-SI ORGANIC-ON-INORGANIC CONTACT BARRIERS

The low-frequency conductance and capacitance characteristics can be used to obtain information about the magnitude and energy distribution of surface states in inorganic semiconductor bandgap. Also, the carrier concentration profiles of the substrate can be conveniently obtained. This technique is applied to OI diodes using thin films of copper phthalocyanine (CuPc) and 3, 4, 9, 10 perylenetetracarboxylic diimide (PTCDI) vapour-deposited onto p-Si substrates. It is found that the densities of surface states for CuPc/p-Si heterojunction vary between 10(12) to 10(14) cm-2 eV-1 while for PTCDI/p-Si interface it is about 10(12) cm-2 eV-1. Unlike the anhydrides, however, the CuPc appears to interact strongly with the inorganic semiconductor resulting in a high density of interface states.