Investigation of luminescence from SiC nano-granule films on porous glass substrate

Abstract

SiC granule films were fabricated onto porous glass substrate by RF-magnetron sputtering. Photoluminescence (PL) measurements show that there are light emissions at three different wavelengths. Ultraviolet emission peaked at 360 nm originated from the band-band transmission of SiC nanoparticles with relatively small size. The 370 nm light emission was due to the luminescence of the nano-skeletons of porous glass that was formed during the etching of the glass substrate. The blue emission at about 460 nm was associated with the recombination of the excited electron and O-deficient defects appeared at the interface between SiC nanoparticles and the porous glass. Furthermore, the optimal PL performance was obtained when SiC deposited time was 1 h and the glass substrate was etched for 20 min in the annealing sample (450 o C). [2][3][4][5][6][7] , the porous SiC [8,9] , the rare-earth doped SiC [10][11][12] and the SiO 2 -related materials [13] , have been extensively studied. Among them, silicon carbide has attracted special interests because it has potential applications on optoelectronics devices and high-temperature mechanical devices. Tan et al. [14,15] have fabricated -SiC films containing both SiC and Si nanocrystallites. Blue emissions at two distinct wavelengths were explained by the radiative recombination of carriers taking place in a kind of silicon excess defect centers at the surfaces of SiC crystallites, whereas the photogeneration of carriers partially occured in the SiC crystallite cores. Liu et al. [16] have also fabricated SiC nanocrystals embedded in SiO 2 matrix by radio-frequency (RF) sputtering and high-temperature annealing. In the case, the observed blue luminescence and green luminescence were thought to originate from the SiC nanoparticle and C nanocluste, respectively. On the other hand, Wang et al. [17] have fabricated SiC/Si/SiO 2 multi-layer films. Two PL peaks were attributed to excess Si defect centers and SiC nanocrystalline. Although many studies have been carried out in order to explain the origin of the luminescence of the indirect-gap group-IV semiconductor and the expected effective light emission, the PL mechanism of SiC-based materials still remains an open question.In the present work, SiC nano-granule films onto the porous glass substrate were fabricated for the first time by RFsputtering technique. Such a special structure gives rise to unique photoluminescence performance. In the experiment, ultraviolet (UV) emission peaked at 360 nm, 370 nm and the blue emission peaked at about 460 nm were observed. Their luminescence mechanism was further discussed in this paper. According to our knowledge, it is the first report about the photoluminescence study of such a structure.The SiC films were prepared on the porous glass substrate by a conventional RF-magnetron sputtering technique. Before the deposition, the glass substrate was dipped in hydrofluoric acid for different time (10 min, 20 min and 30 min) to form porous structures. The substrate was then ultrasonicly cleaned in eth...