Effect of Remote Oxygen Scavenging on Electrical Properties of Ge-Based Metal–Oxide–Semiconductor Capacitors

Remote oxygen scavenging has been studied in a metal/high-k dielectric/GeO2/Ge stack, where a thin Ti layer inserted into the metal/high-k dielectric interface serves as the scavenger. First, we established that remote oxygen scavenging indeed occurs specifically in the studied HfO2/Al2O3/GeO2/Ge stack. It was also established that the source for oxygen is decomposition of the GeO2 layer. Then, the effect of remote oxygen scavenging of the GeO2 layer on the electrical characteristics of the metal/oxide/Ge capacitors was investigated. The electrical properties were studied in comparison with identical gate stacks with a Pt electrode, before and after annealing. Although a decrease in effective oxide thickness was demonstrated as a result of this process, clear degradation of the interface electrical quality was observed after scavenging. Initiation of the scavenging process was witnessed upon deposition of Ti at room temperature, emphasizing that this process could not be controlled.