On resolving the anomaly of indium-tin oxide silicon junctions

Experimental evidence is presented to resolve the anomalous rectifying behavior of indium-tin oxide (ITO)/silicon junctions. Previous work has demonstrated that the rectifying direction for this heterojunction depends on the method used to deposit the ITO. It is shown here that the cause for this is the existence of damaged surface layers in junctions subject to ion beam processing. Irrespective of the material deposited and irrespective of the doping type, ion-beam sputtering tends to cause the silicon band edges to bend downwards at the surface. It is for this reason that ion-beam deposited ITO gives a rectifying junction on p-Si and an ohmic contact on n-Si.