The Effect of a Metal Intralaver on the Heterojunction Band Offset: Extrinsic and Intrinsic Charge Neutrality Levels

The effect of an Al metal intralayer on the ZnSe-Ge heterojunction band offset has been theoretically analysed using a consistent tight-binding calculation. In our analysis we show: (i) first, that the heterojunction band offset is basically modified by the first metal monolayer deposited at the interface; (ii) the changes in the band-offset are mainly due to the modifications introduced in the charge neutrality levels of the semiconductors forming the junction. This implies that extrinsic charge neutrality levels are responsible for the actual heterojunction band offsets. We have also considered different geometries for the first stages of the Al deposition at the interface. Our analysis of the band offset and the core level shift of the Al intralayer allows us to propose a model for the geometry of the growing metal.