H-induced effects in luminescent silicon nanostructures obtained from plasma enhanced chemical vapor deposition grown SiyO1−y:H(y>1∕3) thin films annealed in (Ar+5%H2)

Abstract

Articles you may be interested inExcitation mechanism and thermal emission quenching of Tb ions in silicon rich silicon oxide thin films grown by plasma-enhanced chemical vapour deposition-Do we need silicon nanoclusters?Composition, structural, and electrical properties of fluorinated silicon-nitride thin films grown by remote plasmaenhanced chemical-vapor deposition from SiF 4 / NH 3 mixtures J. Vac. Sci. Technol. A 22, 570 (2004); 10.1116/1.1699335Hydrogenated amorphous silicon carbide deposition using electron cyclotron resonance chemical vapor deposition under high microwave power and strong hydrogen dilution Si y O 1−y :H ͑y = 0.36 and 0.42͒ alloy films were fabricated by electron cyclotron resonance plasma enhanced chemical vapor deposition and subsequently annealed in ͑Ar+5%H 2 ͒ at different temperatures. Glancing angle x-ray diffraction and Fourier transform infrared spectroscopy measurements revealed the formation of silicon nanoclusters ͑Si-ncl͒ in an amorphous SiO 2 matrix for films annealed at temperatures of 900°C and above. Negligible photoluminescence ͑PL͒ was observed at room temperature for the as-grown samples; however, PL bands appeared in the visible after the annealing treatments. The PL intensities are much higher and the spectra skewed to the red as compared to data obtained for similar samples annealed in pure Ar. These effects are attributed to the passivation by H atoms of nonradiative recombination centers in the materials annealed in ͑Ar+5%H 2 ͒. The overall analysis of the PL data indicates that both quantum confinement and defect states contribute to the luminescence. Two-step annealing procedures ͓in Ar and then in ͑Ar+5%H 2 ͔͒ were found to yield slightly higher passivation efficiencies than single annealing steps in ͑Ar+5%H 2 ͒.

The role of quantum confinement and crystalline structure on excitonic lifetimes in silicon nanoclusters

“…We propose that this is evidence for significant contributions of the so called "exciton hopping mechanism" 5 to the total decay rate. Higher Si content is known to yield larger Si-ncl mean size 10,18 and, as the present Raman data show ͓Fig. 2͑b͔͒, to larger Si-ncl density for fixed annealing conditions.…”

“…1 for samples with y = 0.36, 0.39, 0.42 ͑blue, black, and red lines, respectively͒ annealed under Ar+ 5%H 2 at 1100°C, in qualitative agreement with the proposed excitonic QC mechanism of light emission. 9,10 The optical properties of the Si-ncl were studied by using PL, confocal Raman, and time-resolved PL spectroscopies. All measurements were made at room temperature.…”

Raman scattering from confined acoustic phonons of silicon nanocrystals in silicon oxide matrix

“…Figure 1(b) shows the annealing-induced variation of FTIR absorbance spectra measured for the set of samples with x = 0.40. The broad bands with maxima between 1000 and 1100 cm −1 are assigned to the asymmetric stretching motion of the oxygen atom of the Si-O-Si bridging configuration [29]. As can be seen from Fig.…”

“…While Si-Si bonding is Raman active, Si-O-Si bonds are active in the infrared and therefore the matrix properties can be studied by FTIR spectroscopy [29]. Figure 1(b) shows the annealing-induced variation of FTIR absorbance spectra measured for the set of samples with x = 0.40.…”

Éxcitons em nanocristais de silício

“…Taxas radiativas maiores para Si-ncls amorfos hidrogenados podem ser explicadas por efeitos de localização dos portadores de carga em estados localizados 50,206. Estes resultados sugerem que Si-ncls tratados a 900 °C ainda estão amorfos em concordância com outros trabalhos63,179 . Provavelmente, a maior influência na variação das taxas de DBs).…”