Many experimental results and theoretical analysis diverge mostly because different preparation conditions can seriously affect on PL properties of porous silicon. Specimens of porous silicon were prepared under different conditions by double cell positive pole oxidizing method and their photoluminescence properties were analyzed systematically. Firstly

specimens were prepared in the same solution concentration (V (HF): V (C

2

H

5

OH)=1:1) and erosion time (20 min) but under different oxidizing current density. Secondly

specimens were prepared in the same solution concentration (V (HF): V (C

2

H

5

OH)=1:1) and current density (3mA/cm

2

) but for different erosion time. Thirdly

specimens were prepared in the same current density (3mA/cm

2

) and erosion time (20 min) but with different solution concentration. And then photoluminescence spectra of these specimens were measured at room temperature. Fourthly

photoluminescence spectra of the specimen

which prepared under the conditions of solution concentration (V(HF): V(C

2

H

5

OH)=1:1) and current density (3mA/cm

2

) and erosion time (20 min)

were measured respectively at room temperature after it had been lain in the air for three days

sixteen days and thirty days. Results suggest that

with the increasing of the current density

erosion time and the aging time

the peaks of PL shift to the blue

and the intensity of peaks is enhanced. But excessive current density and erosion time would cause the decrease of PL intensity. As for the solution concentration

peaks shift to the red when solution concentration is less than 1:1 but shift to the blue when solution concentration is greater than 1:1 with the increase of solution concentration. Above phenomena can be interpreted by quantum confinement model and light center model

as well as the action of Si-H bonding and other defects. In the process of porous silicon photoluminescence

peak shift and intensity change by current carrier limitation and surface passivation action. Increasing current density can produce more pits during initial stages of erosion

and can enhance hole energy in bulk silicon

and it is favorable for F

-

to go through potential barrier located at Si/HF interface to silicon surface

therefore quantum wire produced at silicon substrate can become thinner. To prolong erosion time can make quantum wire thinner too. The influence of solution concentration is more complex. The influence of aging time on peak position and intensity is obvious

and show that porous silicon quality is not steady.