Scanning room-temperature photoluminescence in polycrystalline silicon

Abstract

Photoluminescence (PL) mapping was performed on polycrystalline silicon wafers at room temperature. Two PL bands are observed: (1) a band-to-band emission with a maximum at 1.09 eV, and (2) a deep “defect” luminescence at about 0.8 eV. PL mapping of 10 cm×10 cm wafers revealed inhomogeneity of the band-to-band PL intensity which could be correlated to the distribution of minority carrier diffusion length in the wafer bulk. We have also observed that the intensity of the 0.8 eV band is strongest along those grain boundaries where the band-to-band PL is suppressed as well as minority carrier diffusion length. The origin of the 0.8 eV luminescence band is discussed.