Nickel induced phase separation and nanocrystal growth in Si-rich silica films

In this study, we introduce a thin nickel interlayer to enhance the phase separation and silicon nanocrystal (Si-NC) growth in Si-rich silica films. Through TEM analysis, it is observed that the Si-NC density in the sample with a Ni interlayer is 2.6 times higher than that of the sample without Ni after high temperature annealing. The photoluminescence (PL) spectrum of the sample with a Ni interlayer is 2-5 times stronger than the one without Ni according to different silicon excess. By analysing the samples after rapid thermal annealing (RTA) with Fourier transform infrared absorption (FTIR), we find that nickel can induce phase separation in Si-rich silica films during annealing. Thermodynamic and kinetic analysis indicates a reduction of 31.4 kJ mol(-1) in the Si-NC nucleation activation free energy by adding the nickel interlayer, which subsequently results in higher Si-NC density.