Cathodoluminescence of small silicon nanoparticles under electron-beam excitation

The temperature (300-25 K) behavior of visible luminescence from silicon nanoparticles in thin films under electron-beam bombardment [cathodoluminescence (CL)] is reported. Emission signals occur near 420, 450, 630, and 750 nm. Unlike cathodoluminescence of fused silica or heavily oxidized porous layers, which is known to fade with cooling, the nanoparticle films are found to exhibit luminescence that variously fade away or grow with cooling. The CL bands of the film are also observed in the photoluminescence spectra under 365- and 254-nm excitations. There is an approximate coincidence of the peak energy observed for the photoluminescence and CL spectra. The temperature behavior of the cathodoluminescence points to a strong contribution from spatial quantum confinement at nanostructures.