N-type porous silicon doping using phosphorous oxychloride (POCl3)

We report here a novel way to dope porous silicon layer with phosphorous by thermal diffusion, using a phosphorus liquid source of phosphorous oxychloride (POCl3) doping technique. The usage of gas for doping the porous skeleton allows this technique to be much more effective than the other doping techniques that were presented before. Five orders of magnitude decrease in the resistivity of the porous layer was measured after the thermal doping followed by an etching process to remove the oxide which is formed during the diffusion and activation process. A significant increase of the photoluminescence was observed after the doping process. After subsequent etching of the thermal oxide, which is formed in the doping process, the photoluminescence retained the same intensity and peak wavelength exhibited by the layer before the process.