Confinement Effects of Phosphorus Donors Embedded in Silicon Microcrystals

Abstract

Due to their extended electronic structure shallow donors are believed to be very sensitive to confinement effects. Our interest is to investigate the influence of size on the properties of shallow donor phosphorus in mechanically milled silicon microcrystals. The crystallinity of powders is confirmed by X-ray diffraction and the size as determined by scanning electron microscopy was found to be 0.25 mm for smallest to 4 mm for largest microcrystals. In the current experiment we use electron paramagnetic resonance to measure the hyperfine interaction between donor electron and P nucleus. The hyperfine constant and mutual overlap of donor wave functions exhibit significant dependence on grain size and subsequent annealing. By photoluminescence spectroscopy the appearance of a strong band around 1515 nm which shifts to higher energies with diminishing grain size has been established.