BAND-STRUCTURE AND CONFINED ENERGY-LEVELS OF THE SI3N4 SI/GAAS SYSTEM/

The band structure of strained Si (4-10 ML) on (001) GaAs, band lineup s of the strained Si/(001)GaAs heterojunction, and confined energy lev els. of the Si3N4/Si/GaAs quantum well have been calculated via a pseu dopotential method. It has been found that in this technically importa nt Si3N4/Si/(001)GaAs structure, strained Si has a very narrow band ga p (0.34 eV) at the Delta(perpendicular to) point in the Brillouin zone . For the strained Si/(001)GaAs heterojunction, the conduction band of fsets from the Delta(perpendicular to) for Si to the Gamma valley for GaAs is 0.83 eV, and that from the Delta(perpendicular to) valley for Si to the X valley for GaAs is 1.21 eV. The valence band offset is 0.2 5 eV. The lowest confined energy level in the conduction band of the S i3N4/Si/GaAs quantum well ranging from 4 to 10 monolayers is found to be 0.22-0.28 eV above the conduction band edge of strained Si, or 0.57 -0.61 eV below the conduction band edge of GaAs, while the first confi ned energy level in the valence band is barely above the Valence band maximum of GaAs. The accumulation and inversion take place at these co nfined energy levels. (C) 1997 American Institute of physics.