S. Mankefors

Semiconductor polar surfaces: mechanisms of the stability of non-reconstructed III–V (1̄1̄1̄) surfaces

Abstract The mechanisms of the stability of bulk terminated semiconductor polar (111) surfaces are investigated for the first time with ab initio methods. In the cases of InAs(111), InP(111) and GaP(111), charge is found to be removed from the surfaces, which avoids an electrostatic catastrophe and stabilizes the surfaces. These new findings properly account for the experimental existence of these unreconstructed surfaces. The GaAs(111) surface is, however, predicted to be unstable in accordance with experiment.

Theoretical investigation of soft x-ray emission from a Si(100) layer buried in GaAs

Calculations of the soft x-ray emission spectrum have been carried out on a buried Si(100) layer in GaAs and compared with experimental data. We find that Si occupies Ga- as well as As-sites and that the local density of states is different for these two cases.

A theoretical investigation of ideal III–V (211) surfaces

Abstract Ab-initio methods are used for the first time to investigate the geometrical and electronic structure of ideal III–V (211) semiconductor surfaces. Very large relaxations are found, and the (211)A and (211)B type surfaces show extensive differences in the atomic positions of the topmost atomic layers. Smaller but distinct differences in atomic relaxations between GaAs and other III–V systems are also found and properly explained. All surfaces become metallic due to the dangling bonds, and a variety of surface states and resonances are investigated.

Hydrogenation of As/Ge(100) 2×1: a theoretical study of the surface electronic structure

Abstract Arsenic deposited on Ge(100) has been investigated by means of ab initio LDA calculations. The results support a previous interpretation of photoemission data in terms of symmetric As dimers. Additional new surface states have been found in an energy range not investigated experimentally. Upon adsorption of hydrogen the As dimer bonds become much weaker, resulting in an essentially increased As–As separation. The modified surface state band structure is predicted to contain some features which should be clearly visible in photoemission spectra.

Electronic structure of ultrathin AlAs(100) layers buried in GaAs

Abstract The electronic structure of 1, 2 and 5 monolayers (ML) of AlAs(100) buried in GaAs has been investigated by ab initio calculations. Distinct differences are observed in the density of states (DOS). In particular, interface states are found for the 1-ML case and the outermost layer of the thicker slabs.

Direct observation of interface effects of thin AlAs(100) layers buried in GaAs

A study of the electronic structure of ultrathin AlAs layers buried in GaAs(100) and their interfaces is presented. Al L-2,L-3 soft-X-ray-emission (SXE) spectra from the AlAs layers were measured. ...