Surface Science 409 (1998) 474–484 Geometry and electronic structure of InP ( 001 ) ( 2×4) reconstructions W.G. Schmidt *, F. Bechstedt Friedrich-Schiller-Universita ¨ t, Institut fu ¨r Festko ¨ rpertheorie und Theoretische Optik, Max-Wien-Platz 1, 07743 Jena, Germany Received 23 January 1998; accepted for publication 24 February 1998 Abstract We investigate the atomic and electronic structure of the InP(001) surface by means of first-principles pseudopotential calculations within density-functional theory. We are able to rule out (4×2) reconstruction models as well as trimer configurations proposed recently as possible equilibrium structures. We predict (2×4) reconstructions characterized by asymmetric In–P or symmetric P dimers for an In-rich and a balanced surface stoichiometry, respectively. For a very limited range of preparation conditions we cannot exclude, however, the existence of further stable (2×4 ) reconstructions. All favourable equilibrium structures are characterized by filled and empty surface bands close to the bulk valence and conduction band edges, respectively. Details of the geometry and electronic properties for the various possible surface reconstructions are given and compared with the experimental data available. © 1998 Elsevier Science B.V. All rights reserved. Keywords: Density functional calculations; Indium phosphide; Molecular dynamics; Single crystal surfaces ( low index single crystal surfaces) 1. Introduction to lead to a (2×4) reconstructed surface [9,10] [the authors of Ref. [9] favour an In-trimer model which corresponds to a (2×4) reconstructed sur- The atomic structure of the polar (001) surface of III–V compound semiconductors is relatively face according to the usual notation]. A (2×4) translational symmetry has also been found to complicated. While the microscopic structure of GaAs(001) now seems to be well understood, result from the decapping of metal-organic vapour- phase epitaxy (MOVPE) grown samples [11,12] there are open questions concerning the InP(001) surface. It has been claimed that ion bombard- and from heating of the oxidized surface [13]. This agrees with the outcome of chemical-beam epitaxy ment and annealing of InP(001) result in a (4×2)/c(8×2) reconstructed, In-rich surface [1– [14] and molecular-beam epitaxy (MBE) experi- ments [15,16]. Yang and Hasegawa [17] observed 7], in analogy to Ga-rich GaAs(001) surfaces [8]. Recently, however, this treatment has been shown a (2×4) reconstruction during gas-source MBE for both P-rich and In-rich InP(001) surfaces. Also the reconstruction mechanism acting on * Corresponding author. Present address: North Carolina InP(001) surfaces is under discussion. A wide State University, Department of Physics, Box 8202, Raleigh, range of atomic structures have been suggested for NC 27695-8202, USA. Fax: +1 919 515 7331; e-mail: wgs@batman.physics.ncsu.edu the surface. Based on high-resolution electron 0039-6028/98/$19.00 © 1998 Elsevier Science B.V. All rights reserved. PII: S0039-6028(98)00260-X