The Fabrication And Characterization Of The Composite Structure Of Porous Silicon/nano-metal Particles

Since Canham discovered the room-temperature highly efficient luminescence of visible light from porous silicon (PS) produced by electrochemical etching in 1990, a large number of interests have been evoked to understand all aspects of PS. PS has many unique properties such as enormous intermal surface, high resistance ratio, high chemical activity, etc. PS has been developed in many application fields including optoelectronics, thermoelectric materials, sensor, microwave/radio frequency microelectronics, biomedicine, etc. This dissertation focuses on the fabrication and characterization of PS/metal compound structure by chemical deposition, which can successfully obtain uniform metal layer that is deeper into the PS pores than sputtering and chemical vapor deposition (CVD). Moreover, the chemical deposition is relatively simple and economical. And by the proposed method some results have been achieved as follows:Copper has been deposited on porous silicon successfully by electroplating. The existence of cubic copper nano-particles (～30nm) into porous silicon matrix was verified by X-ray Diffraction and cross-section Scanning Electron Microscopy (SEM). This experiment has formed the compound structure of PS/metal, however almost no copper particles were found by immersion from SEM. The transverse resistance of the compound structure of M/PS measured by four-probe is founed to decrease apparently. And this changes the characteristic of high resistance of PS, which makes porous silicon more applications.Silver particles have been deposited on porous silicon by thermal decomposition. And Ag films deposited on oxidized porous silicon were characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM). During the experiments we prepared some samples with different porosity and silver particle deposited into respectively. Raman spectrums indicated the appearance of new peaks with silver nanoparticles deposited into porous silicon.The formation of colloidal gold Nano-particles in different diameter by means of sodium citrate reduction was studied in this paper. Gold colloid was deposited on porous silicon by immersion and we found gold nanoparticles with special shapes, e.g.,sphere,tadpole because of the different ratio of HAuCl₄ and sodium citrate. Morever, with the increasing of immertion time, the distributing of single nanogold particles turned into symmetrical nano-thin films.