Modification of GaAs Schottky diodes by thin organic interlayers

Control of the interfacial potential barrier for metal / n- GaAs diodes has been achieved using thin interlayers of the organic semiconductor, tin phthalocyanine (SnPc). The current–voltage (I-V) characteristics for organic-modified Ag / S : GaAs diodes indicate a change from rectifying to almost ohmic behavior as the thickness of the SnPc interlayer is increased. Modeling reveals thermionic emission to be the dominant transport mechanisms for all diodes (ideality factors, n < 1.3⁠). Unlike other organic interlayers in similar device structures, SnPc reduces the effective barrier height by influencing the space charge region of the GaAs. The change in barrier height deduced from the I-V characteristics [(0.26 ± 0.02) V] is similar to the band-bending measured using core-level photoelectron spectroscopy for SnPc growth on the S-passivated n - GaAs (001) surface [(0.22 ± 0.04) eV] and is much larger than previously reported for other similar systems.