Photoluminescence from 20 MeV electron beam irradiated homogeneous SiOx and composite Si-SiOx films

Abstract

The effect of 20 MeV electron irradiation on the room temperature photoluminescence from homogeneous SiO_x and composite Si-SiO_x films, containing amorphous or crystalline Si nanoparticles, is studied. Layers with x = 1.5 and 1.7 and thickness of 200 nm were deposited on crystalline silicon substrates by thermal evaporation of SiO in vacuum. Film annealing in an inert atmosphere at 700 ^oC or 1000 ^oC for 60 min was applied to grow amorphous or crystalline silicon nanoparticles, respectively, in a SiO_x matrix. Samples from all types of films were irradiated with 20 MeV electrons at close to room temperature and a fluence of 2.4x10¹⁴ el.cm^-2. Photoluminescence was measured under excitation with the 488 nm line of an Ar⁺ laser. The electron irradiation causes a decrease of the integrated photoluminescence intensity in composite samples with initial x = 1.7 containing amorphous or crystalline nanoparticles and x = 1.5 samples with Si nanocrystals. The electron irradiation of x = 1.5 samples with amorphous nanoparticles slightly increases the photoluminescence intensity. The obtained results are discussed in terms of electron beam induced phase separation and Si nanoparticle size increase.