Electrical Properties of III-V/Oxide Interfaces

Abstract

We present the interface state distribution at GaAs-oxide interfaces, which consist of two large peaks around mid-gap energies, one donor-like and one acceptor-like, as well as two smaller peaks closer to the band-edge energies, which are responsible for room temperature frequency dispersion in CV-curves. The latter two peaks are strongly reduced by S-passivation treatments as well as forming gas anneals, whereas the mid-gap peaks do not get affected by such treatments. It is argued that the large midgap peaks are likely caused by physical relaxation of the surface due to stress created by the oxidation, with creation of large densities (~1013 cm-2) of As and Ga vacancies at the GaAs surface. The interface state distribution of In0.53Ga0.47As-oxide interfaces is presented as well, which consists of two donor-like peaks, one large peak close to (and partly in) the valence band edge and one smaller peak around mid-gap energies. Such an interface state distribution explains the results obtained by In0.53Ga0.47As-based nMOSFET devices. Here, again, it is argued that these two peaks are likely proper to the In0.53Ga0.47As surface itself, and due to the presence of a large density of vacancies at the surface.