Silicon nanocrystal photoluminescence and electroluminescence modulation studies
|Keywords||silicon nanocrystals laser pre-annealing thermal conductance SiO/Si multi-layer photoluminescence electroluminescence|
The micro-scale optical communication requires light transmitter of microscopic size. Due to its strong photoluminescence and stable structure, the fabrication of silicon nanocrystals embedded in SiO2 matrix (nc-Si:SiO2), is a good choice for the realization of microscopic laser. Among all the chapters, undertaken by the introduction and the fabrication of nc-Si:SiO2, maintained by the modulation of photoluminescence(PL) and the enhancement of electroluminescence(EL) of nc-Si, and terminated by the summary and the prospect, the thesis is finished. The most important are as follows:First, the methodology of CO2 laser pre-annealing is to introduce extra nucleation sites for more nc-Si formation into SiOxthin film so as to suppress the growth of large Si dots and produce extra small Si ones like silicon nanocrystals during the phase separation annealing, the PL of nc-Si:SiO2 was enhanced by a factor of 1. The samples, evaporated on quartz substrates and highly doped p-type Si ones, are respectively irradiated by the same variation of dot densities and power controls of laser. The thermal conductance of quartz is much less than the one of p-type Si, so the SEM map and PL map of the former is clearly modulated while the ones of the latter obscure, which indicates that the thermal conductance plays a very important role in the experiment. Anyway, the PL intensity of nc-Si:SiO2 on both substrates does increase with a maximum of～2-fold.Second, Of all layers that consists of the structure of EL of Si nanocrystal, nc-Si:SiO2 thin film, is mainly investigated. In the very condition of vacuum, more Si nanocrystals are begotten of the inter-diffusion between Si and O atoms by bringing SiO/Si multi-layers in place of single layer of SiOx, meanwhile, the oxygen defects in SiO2 are less generated. CO2 laser irradiating the SiO/Si multi-layer, at last enhances the PL of nc-Si:SiO2 by above 3 times and the EL above 2 times. The peak position and intensity change laws between PL and EL of nc-Si:SiO2 are not in full agreement due to the difference of the luminous mechanism, but along with the increase of laser dot density and power control, the variation tendency of PL and EL intensity reach an agreement, which indicates that both of them become identically indebted to extra nucleation sites from laser pre-annealing.