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 oxychlo ride (POCl3) doping technique. The usage of gas for doping the porous skele ton allows this technique to be much more effective than the other doping t echniques that were presented before. Five orders of magnitude decrease in the resistivity of the porous layer was measured after the thermal doping f ollowed by an etching process to remove the oxide which is formed during th e diffusion and activation process. A significant increase of the photolumi nescence was observed after the doping process. After subsequent etching of the thermal oxide, which is formed in the doping process, the photolumines cence retained the same intensity and peak wavelength exhibited by the laye r before the process.