Interface properties of Al2O3/Ge structures with thin Ge oxide interfacial layer formed by pulsed metal organic chemical vapor deposition

Abstract

We have examined the formation of a thin GeO2 layer on a Ge substrate by pulsed metal organic chemical vapor deposition (MOCVD) using tetraethoxygermanium (TEOG) and H2O to precisely control GeO2 layer thickness. Also, we have investigated the feasibility of the use of a thin GeO2 layer formed by pulsed MOCVD at the Al2O3/Ge interface. Pulsed MOCVD enables thin GeO2 layer formation with thickness control by the self-limited adsorption of TEOG. For the growth of a thick GeO2 layer, it is a key to allow TEOG and H2O molecules to sufficiently react. Furthermore, we found that the MOCVD-GeO2 layer has a high etching tolerance to Al2O3 deposition and can reduce the interface state density of the Al2O3/Ge structure. Therefore, GeO2 formation by pulsed MOCVD using TEOG and H2O is a candidate method for realizing high-quality high-k/Ge gate stacks.