Passivation Mechanism of the Native Oxide/InAs Interface by Fluorine

Abstract

Comparative experimental and theoretical studies of the fluorine/oxygen ratio influence on the structural and electronic properties of the anodic layer (AL)/InAs interface by XPS, HRTEM, C–V (77K) measurements and ab initio calculation of fluorine and oxygen adsorption on the InAs(111)A-(1 × 1) unreconstructed surface were performed. The well-ordered transition layer (TL), composed of indium and arsenic oxyfluorides, and extension of the interplanar distance at the fluorinated anodic layer (FAL)/InAs interface were experimentally revealed. The theoretical modeling of AL/InAs and FAL/InAs interfaces showed that the fluorinated TR formation removes the InAs surface distortion, whereas the In(InAs)–F–As(FAL) and In(InAs)–O–As(FAL) bond formation is a reason for the interplanar distance increase between FAL and the InAs surface. The decrease of the interface state density in the InAs bandgap and the Fermi level unpinning at the FAL/InAs interface result from the positive charge increase on FAL arsenic atoms near the InAs surface during the As–F bonds formation, while the electron accumulation on oxygen atoms and InAs subsurface arsenic atoms is the reason for the states appearance in the InAs bandgap at the anodic (native) oxide/InAs interface.