Photoluminescence Study of Si1-xGex/Si and Si/Ge Strained Layer Superlattices
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
Pagination or Media Count:
In this dissertation, long-period Si1-xGe.si superlattices grown by MBE at 500 deg C and annealed post-growth using rapid thermal annealing were investigated using photoluminescence PL. The as-grown samples have broad PL bands from isoelectronic centers related to Ge complexes as well as sharp near- edge bound exciton lines. The broad PL band was found to be 120 meV below the band gap, after accounting for the effects of confinement of holes. Annealing resulted in a reduction in the broad PL band activation energies and a shift of the broad band to higher energies. The reduction in the activation energies of the broad band were found to be due to the position of the emission centers within the Si,-.Ge. layers. The emission centers in the middle of the Si,-.Ge. were deactivated at higher temperatures than those at the edges, which caused the shift of the broad band to lower energies as the sample temperature increased. The shifts of the broad PL band as the annealing temperature increased were found to be due to a net shift of the emission centers towards the interfaces. Silicon-Germanium alloys, superlattices, heterostructurest photoluminescence, SiGe, semiconductor alloys, optical properties.
- Industrial Chemistry and Chemical Processing
- Physical Chemistry