FORMATION OF A SCHOTTKY-BARRIER BETWEEN EUTECTIC GA,IN AND THIOPHENE OLIGOMERS

The formation of a Schottky barrier between an eutectic (Ga,In) alloy and a highly doped thiophene oligomer is followed as a function of tim e using current density-voltage and capacitance-voltage measurements. Within 1 h, the diode characteristics change from almost nonrectifying , leaky behavior into a rectification ratio of 10(4) with a considerab ly reduced leakage current. Measurements and energy band diagram calcu lations show that the depletion width increases with time due to a dec rease in the ionizable acceptor density of the semiconductor at the Sc hottky interface. This is probably caused by a chemical reaction betwe en the in-diffusing metals and the doped oligomer. (C) 1997 American I nstitute of Physics.