The relationship between minority carrier life and morphology with luminescent properties in porous silicon was studied.The surface morphology of the porous silicon(PS)samples was observed by the field emission scanning electron microscopy(FESEM)and the atom force microscopy(AFM)and microwave photo-conductance decay(μ-PCD)technique was first used to measure the minority carrier lifetime of PS.The results show that the porosity of porous silicon increased with the increase of etched time

which lead to the decrease of minority carrier life and the increase of luminescent efficiency of porous silicon.When the minority carrier life of PS decreases

the irradiative centers on surface of PS increase

which lead to decreasing of photoluminescence(PL)efficiency.Furthermore the results of μ-PCD technique showed the un-uniformity of minority carrier life of PS

which lead to the un-uniformity of PL efficiencies on different location of PS surface.This result proved that the formation of PS is depending on current density and back illumination strength.The results of the PL spectra and the Fourier transform infrared(FTIR)spectra illuminated that the emission came from the formation of surface confined emitters that related to the defects in silicon dioxides and the hydrogen atoms on surface of PS samples played as a key role to dissipate the irradiative centers and increase the PL efficiency.In addition

the result of morphology observation by atomic force microscopy exhibited that the surface of porous silicon became smooth gradually with increase of etched time

which may be related to the chemical etching during the electrochemical etching process.