| AVS 61st International Symposium & Exhibition | |
| Electronic Materials and Processing | Tuesday Sessions |
| Session EM-TuP |
| Session: | Electronic Materials and Processing Poster Session |
| Presenter: | Esteban Ojeda-Durán, Benemerita Universidad Autónoma de Puebla |
| Authors: | K. Monfil-Leyva, Benemerita Universidad Autónoma de Puebla, Mexico A. Morales-Sánchez, Centro de Investigación en Materiales Avanzados, S.C. A.L. Muñoz-Zurita, Universidad Autónoma de Coahuila F.J. Flores-Gracia, Benemerita Universidad Autónoma de Puebla M. Moreno-Moreno, Instituto Nacional de Astrofísica Óptica y Electrónica E. Ojeda-Durán, Benemerita Universidad Autónoma de Puebla |
| Correspondent: | Click to Email |
Luminescent process in materials based on silicon nanostructures has attracted a great effort to overcome the intrinsic disadvantages of bulk-Si to develop optoelectronic devices. Nowadays, the Silicon Rich Oxide (SRO) and S ilicon Rich Nitride (SRN) arise as a cheap and effective alternative to develop ultraviolet absorbers or silicon-based light emitters. SRO and SRN films can be deposited by several techniques but homogeneous layers can be easily obtained by low pressure chemical vapor deposition (LPCVD) using N2O and NH3 respectively mixed with SiH4 as reactive gases. Silicon excess in SRO and SRN is well controlled by Ro = N2O/SiH4 and Ron = NH3/SiH4.
In this work, we report a wide study of the optical properties of thin SRO and SRN films obtained by LPCVD where silicon excess was changed by the pressure ratio Ro in the range of 15 and 45 (SRO15 to SRO45) and Ron in the range of 4 to 80 (SRN4 to SRN80). The effect of annealing at high temperature was studied at 1100 ºC. Ellipsometry measurements were done on each sample to calculate the thickness and the refractive index. Fourier transform infrared (FTIR) measurements were applied on SRO and SRN films to confirm a change on stoichiometry. Absorbance spectra of SRO films showed the four characteristic peaks of non-stoichiometric silicon dioxide (SiOx) after annealing. The as-deposited SRN films showed the characteristic peaks of a hydrogenated SiNx matrix. However, the Si-H and N-H stretching peaks (2210 and 3315 cm-1) disappeared after applying the annealing. SRN films showed a transmittance of 40 up to 90 % in the visible to near infrared region (400 to 900 nm). SRO films showed a strong photoluminescence (PL) at room temperature (RT) on two bands, a blue band from 400 to 550 nm or a red band from 575 nm to 875 nm depending on Ro. Blue and red emission bands were related to donor acceptor decays between traps promoted by defects. SRN films with high Si excess showed a wide PL from 450 to 850 nm. PL intensity from SRN was reduced when annealing temperature was increased, then the PL was also related to defects in the SiNx matrix.