Photoluminescence from Si: Effect of ripple microstructures induced by argon ion irradiation

We performed photoluminescence (PL) measurements on Si surface irradiated with 60 keV Ar+ at a fixed ion fluence of E18 ions/cm² for two angles of ion incidence, namely 0° (with respect to surface normal of the sample) and 60°. Periodically modulated ripple morphology is observed for a 60° angle of ion incidence. The ripple microstructure consists of amorphous structure on the rear slope and a comparatively thicker amorphous layer with Ar bubbles on the front slope, whereas a uniformly thick amorphous layer with relatively large bubbles is created under normal bombardment. Room temperature PL of the rippled Si shows a visible band with a peak at ~700 nm and a strong infrared (IR) band having a peak at ~1000 nm. However, the visible PL was very weak and no IR emission was observed for normally irradiated Si.