Passivation Challenges with Ge and III/V Devices

Ge and III/V materials are investigated as high mobility channel materials for devices beyond the 14 nm technology node. Passivation of the interface is a prerequisite as dangling bond states trap charges and reduce the mobility. Passivation of the Ge/high-κ interface can be done by using GeO2 as a passivation layer. However, large thicknesses are needed to keep a low defect density. Introduction of S at the interface can solve this issue. Passivation of III/V materials is still a major problem. Oxidation of the III-As surface leads to stress at the surface creating As-As bonds. Oxides can be partially removed by wet treatment or during the ALD deposition. The defects related to As-As bonds cannot be removed by the ALD process. We demonstrate that also for InP, an oxide free interface does not solve the passivation problem.