Orange-green emission from porous Si coated with Ge films : The role of Ge-related defects

Photoluminescence ~PL! spectra of porous Si ~PS! coated with Ge films were examined using the 514.5 nm line of Ar 1 laser. A new orange-green PL band, centered at 2.25 eV, was observed with full-width at half-maximum of;0.1 eV, in addition to the reported PL bands at 3.1, 2.0, and 1.72 eV. With increasing the thickness of Ge layer coated, the new PL band… (More)