Copper Doped Porous Silicon Photoluminescence And Photoconductive Properties Of Porous Silicon

There is a long history of study on porous silicon (PS), but the research on this material has entered a new phase since the report of the visible light emission out of porous silicon at room temperature by Canham in 1990. This discovery pioneered a new way for the development of Si-based light-emitting devices and optoelectronic devices. Compared with crystalline silicon which has indirect band gap, PS has many advantages such as simply prepared method, lower-cost, complex constructure characteristics, higher photoluminescence efficiency, better photoelectric properties etc. For these reasons, PS has promising potential in the field of optoelectronic and display technology materials. Furthermore, because of its higher photosensitivity, PS shows favorable application prospects in photoelectronics field. As a silicon-based material, PS can match with silicon technology easily. So once applied luminescence devices is made from PS, it will give birth to a new silicon-based material which will expand the application of Si technology from microelectronics to photoelectronics field, and even have a tremendous influence on the future electronic devices as well as the whole field of electronics.In this paper, according to the strong visible photoluminescence (PL) from porous silicon and its higher photosensitivity, its photoluminescence properties and photoconductivity (PC) characteristics was studied. At the same time, the PL mechanism of PS was further discussed.In the first chapter, the history of study on porous silicon was reviewed in brief, including the prepared technics and the microstructure of PS. Then the luminescence and photoelectric properties of this material was discussed at last.In the second chapter, the luminescence characteristics and PL mechanism of PS was mainly discussed. PS radiation mechanism has been discussed and investigated for many years .and many theoretical models have been proposed todescribe the photoluminescence in PS, for instance, quantum confinement effect model, polysilanes model, surfacial states model and quantum confinement-light center model etc. But the PL mechanism of PS is still a controversial issue. Luminescence and quenching are two courses which oppose and compete with each other in the luminescence materials. So in order to grasp the luminescence mechanism of PS, it is very important to study its luminescence and quenching. We reported the optical properties of copper-doped porous silicon by immersion plating in metal ion solutions (CuSO4). Immersion or electroless plating refers to the adsorbing of copper ions onto the Si nanocrystallites in the PS layers by immersing PS into the CuSO4 solutions without applying a bias. In order to research the influence on the photoluminescence of copper-doped PS, the photoluminescence spectra and the Fourier transform infrared (FTIR) spectroscopy of PS was measured. This study indicated that the PL of PS was quenched by copper-doping, and the blue shift of the PL peak locations was found too. At the same time, the PL mechanism of PS was further discussed. In addition, it was found that immersion plating was a good method for metal deposition on the surface of semiconductors.The third chapter was about the photoconductivity characteristics of PS. It is precondition for the application of PS material to study on the photoconductivity characteristics of PS. PS has higher photosensitivity and better photoconductivity response. In this chapter, we studied the photoconductivity characteristics of porous silicon under different intensity of illumination, wavelength, applied voltage and prepared conditions. Experiments indicated that PS had a good photoconductivity effect in the range of visible light, and the highest photosensitivity was found to be around wavelength of 500~600nm. The recombination included the processes of both monomolecular and bimolecular in the PS layers. Moreover the band gap of PS was about 1.85eV, which could be obtained easily from the photoconduction spectra of PS. With the bias voltage increasing, the photo...