Improved infrared photoluminescence characteristics from circularly ordered self-assembled Ge islands
1 Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur 721302, India
2 DST Unit for Nanoscience, S N Bose National Centre for Basic Sciences, Block JD, Sector III, Kolkata 700098, India
Nanoscale Research Letters 2011, 6:416 doi:10.1186/1556-276X-6-416Published: 9 June 2011
The formation of circularly ordered Ge-islands on Si(001) has been achieved because of nonuniform strain field around the periphery of the holes patterned by focused ion beam in combination with a self-assembled growth using molecular beam epitaxy. The photoluminescence (PL) spectra obtained from patterned areas (i.e., ordered islands) show a significant signal enhancement, which sustained till 200 K, without any vertical stacking of islands. The origin of two activation energies in temperature-dependent PL spectra of the ordered islands has been explained in detail.