In-situ study of emerging metallicity and memory effect on ion-beam bombarded strontium titanate surface.

摘要

In this work we present an investigation of the occurrence of conductivity on the surface of SrTiO3 due to argon ion bombardment. We created a model to describe this process and found that the temperature during the ion milling is a crucial factor for the conductivity. Depending on the temperatures we found surface carrier densities ranging from nS = 1:5 x 1018 to 2:6 x 1020 cm -3 by just analyzing the conductivity behavior.;Clustering of vacancies goes along with temperature and affects the conductivity significantly. Furthermore we found that ion milling is a gentle way to create vacancies because the clustering rate is small compared to annealing samples in high vacuum. The amount of clusters at room temperature was measured to be around 3-4 times higher than at -140°C.;We found that samples with a conducting surface change their resistance over time at room-temperature due to the ongoing process of oxygen vacancy clustering. This effect may be suppressed by decreasing the temperature.;The bistable switching behavior in oxygen deficient SrTiO3 is shown without any additional doping. The vacancy migration is the major mechanism behind this memory effect. Comparing this behavior with annealed samples in high vacuum shows that the therein present amount of vacancy clusters must be much larger and has a negative effect on the bistable switching behavior.