White-light and infrared emission from Silicon Oxycarbide-based materials.

摘要

The development of a Si-based light source has attracted a high level of attention due to its potential unique advantages. For one, the monolithic integration of photonics on on-chip level along with the microelectronics devices would enhance the data processing rate. Additionally the cost per transmitted/processed information capacity can be significantly reduced.;In this Ph.D. thesis work, amorphous silicon oxycarbide (SiCxOy) is proposed as an active medium for light emission in visible and IR (when doped with Er ions). More specifically, strong room-temperature white luminescence emitted from SiCxOy films grown by thermal chemical vapor deposition (TCVD) is reported. The emission spectra from the films cover a broad spectral range, from blue-violet to near infrared, depending on carbon concentration. It is found that excitation of these materials is primarily taking place through the material absorption while two major excitation bands have been also detected at 3.36 eV and 3.55 eV, associated with Si-C cores and C=O related centers respectively. Furthermore, it was found that the photoluminescence (PL) intensity, in green and red emission bands, was well correlated with Si-O-C bond density, determined from the Fourier transform infrared spectroscopy (FTIR) analysis. Further engineering of the luminescent centers with oxygen treatment and advanced structural analysis with electron paramagnetic resonance confirmed the previous results. (≡Si-)3C * radicals, EX centers and neutral oxygen vacancies were found to exhibit correlation with the matrix luminescence.;The infrared emission of Er ions doped in silicon oxycarbide, around 1540 nm (intra-4f Er3+ transition from 4I13/2 to 4I15/2), was also studied. A broad-band excitation behavior was found, suggesting that the energy transfer is matrix assisted. Additionally, the excitation of Er ions was also found to take place through the 3.36eV excitation band and/or the 0.86 eV relaxation between the 3.36 eV and 2.5 eV green emission bands, associated with the Si-O-C structure. This suggests that the matrix luminescence centers of SiCxOy play the role of sensitizers for Er ions.