| AVS 62nd International Symposium & Exhibition | |
| Thin Film | Monday Sessions |
| Session TF+2D+MG+NS-MoA |
| Session: | ALD, CVD, MLD, and PLD on Special Materials |
| Presenter: | Karim Monfil-Leyva, Benemérita Universidad Autónoma de Puebla, Mexico |
| Authors: | K. Monfil-Leyva, Benemérita Universidad Autónoma de Puebla, Mexico A.L. Muñoz-Zurita, Universidad Politécnica Metropolitana de Puebla, Mexico E. Ojeda-Durán, Benemérita Universidad Autónoma de Puebla, Mexico A. Benítez, Benemérita Universidad Autónoma de Puebla, Mexico J. Carrillo-López, Benemérita Universidad Autónoma de Puebla, Mexico J.A. Luna-López, Benemérita Universidad Autónoma de Puebla, Mexico R.C. Ambrosio-Lázaro, Benemérita Universidad Autónoma de Puebla, Mexico |
| Correspondent: | Click to Email |
Currently, electronics and semiconductor studies have focused a great effort to overcome the intrinsic disadvantages of bulk-Si to develop optoelectronic devices. In particular, the Silicon Rich Oxide (SRO) has been proposed as a cheap and effective alternative to develop ultraviolet absorbers or silicon-based light emitters. SRO can be deposited by several chemical vapor deposition techniques like Low Pressure Chemical Vapor Deposition (LPCVD) or Hot Filament Chemical Vapor Deposition (HFCVD). Silicon excess in SRO films obtained by LPCVD can be controlled by pressure ratio Ro = N2O/SiH4. Meanwhile, silicon excess in SRO films obtained by HFCVD can be controlled by changing the hydrogen flow (HF).
In this work, we report a study of the optical and structural properties of thin SRO films obtained by LPCVD and HFCVD. Silicon excess was changed by the pressure ratio Ro in the range of 15 and 45 (SRO15 to SRO45) and HF was changed between 25 and 75 sccm. SRO LPCVD films were annealed at 1100 ºC. Ellipsometry and step measurements were applied to calculate thickness and the refractive index. Fourier transform infrared (FTIR) measurements were obtained from SRO films to confirm a change on stoichiometry. Absorbance spectra of SRO films showed rocking and bending vibration modes similar to stoichiometric silicon dioxide but an asymmetric stretching mode revealed the non-stoichiometric nature of our semiconductor films. SRO films by LPCVD 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. SRO films by HFCVD also showed a red band from 500 to 1100 nm (depending on the HF) and this emission was attributed to defects produced by the transport of the precursors. SRO films showed suitable optical properties for possible photovoltaic applications.