CHEMISTRY, DIFFUSION, AND ELECTRONIC-PROPERTIES OF A METAL ORGANIC SEMICONDUCTOR CONTACT - IN/PERYLENETETRACARBOXYLIC DIANHYDRIDE/

We present a photoemission investigation of the interface between In a nd 3, 4, 9, 10 perylenetetracarboxylic dianhydride (PTCDA). The interf acial region is very wide due to an anomalously fast diffusion of In i nto the organic layer. In also reacts with the anhydride end groups of the molecules. The absence of metal clustering, which permits diffusi on, is believed to be due to the ionization of In and ion-ion repulsio n in the PTCDA matrix. Finally, the ohmicity of the In/PTCDA contact i s attributed to reaction-induced electronic gap states created through out the wide interfacial region upon formation of the interface. This study provides the first direct correlation between chemistry and elec tronic properties of a metal contact on an organic molecular semicondu ctor. (C) 1996 American Institute of Physics.