Strong visible light emission from silicon-oxycarbide nanowire arrays prepared by electron beam lithography and reactive ion etching

Abstract

The present report presents results from the fabrication, structural, and optical characteristics of sub-100 nm thermal chemical vapor deposition-grown silicon-oxycarbide (SiC x O y ) nanowire (NW) arrays fabricated by e-beam lithography and reactive-ion-etching. The composition of SiC x O y materials follows closely the silicon-oxycarbide stoichiometry [SiC x O 2(1Àx) , (0 , x , 1)] as observed by compositional and structural analysis. The corresponding structural and bonding evolution of SiC x O y are well-correlated with changes in their optical properties, as demonstrated by the linear dependence of their optical gap and refractive index with [Si-C]/[Si-O] bond-area ratio. By virtue of these advantages, properly tailored SiC x O y NWs were fabricated, exhibiting strong room-temperature visible photoluminescence (PL) through engineering of [Si-C]/[Si-O] bonds. The current studies focused on the thermal-oxidation and excitation intensity behavior of SiC x O y NWs revealed their very good stability, as their luminescence characteristics remain unchanged upon annealing in oxygen ambient (250°C), while the PL intensity dependence on the excitation power-density exhibited a linear increase up to ;800 W/cm 2 .

Silicon Oxycarbide Thin films and Nanostructures: Synthesis, Properties and Applications

“…The HSQ patterns then underwent a hardening annealing process in Ar/N 2 ambient at 500°C, followed by a fluorine-based (e.g., combination of CHF 3 and CF 4 gases) anisotropic RIE to transfer the pattern into the SiC x O y thin films. The HSQ residue is then removed by wet etching in buffered hydrofluoric (BHF) acid, resulting in periodically well-defined NWs [22].…”

“…Large SiC x O y NW structures were fabricated on intrinsic Si substrates in order to perform bonding configuration analysis [22]. The normalized absorbance FTIR spectra of both the asdeposited SiC 0.34 O 1.52 thin film and the as-fabricated NWs are shown in Figure 6.…”

“…Therefore, the functionality of such nanostructured materials and their devices can be employed in a ubiquitous way in light emission applications [21]. To this extent, SiC x O y nanowires (NWs) have been recently shown to exhibit strong room-temperature visible luminescence [22][23][24].…”

Structure and properties of white Si–O–C(–H) ceramics derived from polycarbosilane by thermal oxidation curing and H₂ decarbonization process

“…15) Nikas et al, however, claimed that broadband PL spectrum of his SiC x (O 2(1¹x) ) film may be attributed to the inhomogeneous constitution of the electronic states and the band tails in FT-IR spectra related to CSi/ carbon modified SiOSi bonding (such as O (3¹x) C x Ô SiOSiÔC y O (3¹y) ). 16), 17) This issue about the characteristic PL center in SiOC(H) requires further analysis and discussion. Figure 5(a) shows Si K-edge XANES spectra of the SiO C(H) samples after the 800°C decarbonization with references of PCS (units of SiC 4 and SiC 3 H: Peak at 1842 eV) and amorphous silica (a units of SiO 4 : Peak at 1846.5 eV).…”

Strong Photoluminescence Enhancement of Silicon Oxycarbide through Defect Engineering

“…Towards this, SiC x O y nanowires (NWs) have been recently shown to exhibit strong room-temperature visible light emission [10,11]. Additionally, SiC x O y has demonstrated to be a suitable host material for optically active rare-earth ions [12,13].…”