Luminescent And Electrical Properties Of Composites Of Porous Silicon And Organic Materials

Visible light emission from porous silicon films has stimulated tremendous interests over the past several years due to its potential application in optoeletronics devices and its ability to be integrated with current Si-processing technology.This paper investigated the photoluminescence properties and I-V properties of the composites of porous silicon and organic materials by using photoluminescence spectra analysis, I-V curves analysis, infrared analysis, and so on. A new model of p-n junction, porous silicon/organic junction, was suggested. The influence of rapid thermal process in different gases on the photoluminescence properties of porous silicon was discussed.The photoluminescence (PL) property of the composite of porous silicon and PMMA was investigated. The porous silicon (PS) samples were prepared by chemical etching. The PMMA polymer film was precipitated on the surface of PS with different methods. Photoluminescence of porous silicon and PS/PMMA composites has been investigated. The result showed that the spin coating method was better relatively. The obvious blue shift of PL was found in spectra of the PS/PMMA composite prepared with spin coating. Compared to the spectra from original PS sample, the luminescence quenching was greatly decreased for PS/PMMA composite due to the prevention to PS layer with coated with PMMA film and modification of dielectrical penetrability of the medium in quantum threads by the PMMA. The intensity of PL of the composition doesn't decrease with time because PMMA polymer film protects PS surface from atmospheric vapor and gas.The optical and electrical properties of the composites of porous silicon/alumina and organic luminescence materials (PVK,Alqs, DBO-PPV) were also discussed. The PL spectrum of the composite of porous silicon and PVK showed the peak that belonged not only to porous silicon but also to PVK. At the same time, a new peakwas found locating at X =485nm. The l-V characterization of the composite of porous silicon and PVK was measured. The results indicated that the I-V property of porous silicon was improved after coated with a PVK thin film. The similar results were found after Alqs was deposited on the surface of porous silicon. The photoluminescence properties of the composites of porous silicon/ alumina and DBO-PPV were also investigated. Compared with the composite of porous silicon and DBO-PPV, the peak of PL of porous silicon showed a blue shift. Four peaks in the photoluminescence (PL) spectra of the composite of porous alumina and DBO-PPV, which were contributed from both of DBO-PPV and porous alumina, were found. It was also found that the light emitted from porous alumina could excite the PL of DBO-PPV. The nanometer effect of the pores, which increased surface area and caused the failure of conglomeration of DBO-PPV polymer, can lead to the 90nm blue shift of the PL peaks of DBO-PPV.Four blue light emission peaks were found in the PL spectra of porous silicon which was subjected to rapid thermal process (RTP). Similar results can be got after porous silicon samples were subjected to RTP in different gases. After HF dipping, four blue emission peaks in PL spectra still can be observed. So the blue emission was not from SiO2 or the defects in SiO2.It is possible that the blue light emission was from the skeleton of porous silicon.