Theoretical Calculations Supporting Investigation of Metal Contacts to Ultra-Small Semiconductor Structures

摘要

Metal-ultrasmall superlattice junctions have been analysed by using a consistent tight-binding method. Heterojunctions and metal-semicondictor interfaces have been discussed independently by assuming that each semiconductor superlayer has more than six layers. We present results for the electronic structure of (100)-semiconductor heterojunctions; in particular, we consider the (100)-GaAs-A1As, GaSb-InAs and InAs-GaSb interfaces. For GaAs-A1As we have found that the valence band offset is 0.41 eV, and that there is an interface dipole of 0.13 eV (for no interface dipole, the valence band offset would be of 0.28 eV). Our results also show that the two GaSb-InAs and InAs-GaSb interfaces present different band-offset discontinuities. We have also analysed the initial stages of the Schottky-barrier formation for A1 on an As-terminated GaAs-(100) face. Two cases have been analysed: (i) firstly, we have considered a half monolayer of A1, with these atoms located in the ideal position corressponding to a Ga-atom of the ideal continued GaAs crystal; (ii) in the second case, we have considered a full monolayer with the A1 atoms forming a (100)-face of an A1 crystal.