72 nd Annual Physical Electronics Conference Final Program

It was recently found by us that oxygen induces ordered reconstructions on several III-Vsurfaces [1], which is significant, because ordered oxygen-induced reconstructions have not beenreported to III-V semiconductor surfaces having zincblende structure. These reconstructions attractattention due to the immense interest in the development of oxide-semiconductor interfaces for thenext generation metal-oxide-semiconductor-field-effect-transistors (MOSFETs). The formation ofordered oxides is attributed to significant stability of specific oxygen positions in the second surfacelayer, which is due to the exceptional surface structure of the c(8×2)-ζ having III-V intermixed surfacelayer. The most oxygen-rich reconstruction shows (3×1) periodicity. A detailed atomic model ispresented for this reconstruction in addition to the atomic model of the less oxygen-rich c(4×2)reconstruction. The uncommon (3×1) periodicity is attributed to the highly stable In-O-In trilayerbelow surface which also leads to significantly stabilizing additional bonds within the surface layer.The strain induced by the trilayer is more effectively accommodated within the (3×1) reconstructionthan within the competing (2×1) reconstruction due to smaller number of dimers. It is proposed that theexperimentally found semiconductivity is reached by substitutional atoms within the surface layer. Theband gap of the (3x1) reconstruction with substitutional atoms in the surface layer is larger than that ofthe oxygen-induced c(4×2) reconstruction with 0.5 monolayers of oxygen, in agreement with theexperimental results. It is deduced that the (3×1) reconstruction comprises about 1 monolayer ofoxygen based on the electron counting rule and scanning-tunneling-microscopy images. [1] M. P. J. Punkkinen, P. Laukkanen, J. Lång, M. Kuzmin, M. Tuominen, V. Tuominen, J. Dahl, M.Pessa, M. Guina, K. Kokko, J. Sadowski, B. Johansson, I. J. Väyrynen, and L. Vitos, Phys. Rev. B 83,195329 (2011).