AFRL-OSR-VA-TR-2015-0213 Heterointegration of Dissimilar Materials

An in-situ investigation of the interface evolution during MBE deposition of SrTiO3 on Si has been undertaken using x-ray photoelectron spectroscopy. This study revealed that the critical parameter to control the oxide/semiconductor interface is the incident oxygen during nucleation. Increase in oxygen leads to the formation of interfacial SiO2 even though the surface as monitored by RHEED remained 2dimensional; the formation is due to the reaction of Si with oxygen that has diffused through the oxide film. Low oxygen partial pressure leads to unoxidized Ti, a destruction of the interface and the growth of non-crystalline oxide films. The growth of BiFeO3 on SrTiO3/Si with excellent crystalline quality was demonstrated which opens the possibility for oxide semiconductor integration leading to new device architectures.