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Dependence of photoluminescence from a-Si nanoparticles on the annealing time and exciting wavelength

“…As mentioned above, the previous studies performed on SiO x films with x ¼ 1:5 and 1.7 annealed for t a X60 min at 970 K have shown that at such annealing times the intensity of the 2.1 eV PL band related to na-Si decreases and the band red shifts with increasing time. This observation has been attributed [26] to nanoparticle size increase. At the shorter annealing times applied in this study (t a p60 min) the behaviour of this band is quite different.…”

“…In SiO x films (x ¼ 1:121:7) annealed for X60 min at 770 and 970 K and excited with the 488 nm line of an Ar + laser a band has been observed [26,36] peaked in the range 1.8-2.1 eV. In principle, the peak position of this band depends on the film composition, annealing temperature and time.…”

“…3) while the band at 2.1 eV showed only small, not systematic variations of its intensity and position. Since the 2.1 eV band was peaked in the energy range, in which the PL has been assigned [26] to radiative recombination in amorphous Si nanoparticles, one can think this band is also connected with recombination in amorphous silicon nanoparticles. This assumption is in agreement with the IR absorbance results which indicated an initial phase separation in these samples [37].…”

“…These technical problems can be, at least partially, overcome by growing amorphous silicon nanoparticles [22]. They are usually grown upon annealing at Tp970 K [17,[22][23][24][25][26] and, in addition, one can expect that internal strains in na-Si should be smaller than those in nc-Si. It has been observed [17,27] that the PL intensity from SiO x annealed at To1100 K is higher than that from films with the same initial composition but annealed at T41200 K which can be considered as confirmation of this expectation.…”

“…In most articles, the emission has been assigned [28][29][30][31] to radiative recombination via defects. Only a few research groups [23][24][25][26][27]32,33] have related the observed PL to recombination of carriers in the extended states of a-Si clusters formed during annealing of SiO x films.…”