Heterointegration of Dissimilar Materials

The integration scheme for compound semiconductors, functional oxides and silicon has been developed using molecular beam epitaxy with the oxide as a buffer layer on silicon substrates. This scheme will enable multifunctional oxides to be integrated with Si based logic and high speed optoelectronics afforded by III-V compound semiconductors. Various processes were developed whereby functional oxides were epitaxially deposited onto both silicon and compound semiconductor substrates. The oxidesemiconductor interface was studied in an effort to understand the bonding chemistry and the energetics to develop growth processes for 2-dimensional growth of compound semiconductors. Using a combination of high resolution transmission electron microscopy, in-situ XPS and density functional calculation a model of the bonding between the atoms at the SrTiO3GaAs interface emerge. The relative stability of a number of interfacial structures was compared using the Gibbs free energy and for thin oxide layers, the most energetically stable structure was determined to be As-Sr interface with Sr atoms coming from an oxygen-depleted SrO layer. Using 3 terminations of the oxide surface, compound semiconductor layers were deposited by MBE.