The special physicochemical environment caused by sonic-vacating provides an important outlet for the preparation of highly efficient luminescent porous silicon(PS)films.Experiment results show that sonic-chemical treatment is an effective technology for the improvement of the microstructure of porous silicon

the luminescent efficiency and stability thereof.Luminescent porous silicon films

prepared by ultrasonic-enhanced anode electrochemical etching

display better qualities than the samples prepared by conventional methods widely used at present.This ultrasonic-chemical effect roots in sonic-vacating

i.e.the generation

formation and rapid collapse of bubbles in the etching solution.In the process of the PS being etched

the escape rate and caving-in of hydrogen bubbles in the pores is increased as a result of the work of the ultrasonic wave which is helpful to the vertical etching of the pores.It made full width at half maximum of porous silicon photoluminescence peak compress to 3.8 nm.In summary

we have presented an ultrasonic anodic etching method for fabricating light-emitting porous silicon material.Surface and cross-sectional SEM investigations reveal that when other etch parameters are constant

the ultrasonic etching creates a thicker and more uniform porous silicon layer

with smaller silicon pores than that of PS prepared by DC etching or pulsed etching.AFM observations further confirm the improved structural properties

which can be explained by the porous silicon formation mechanics especially by ultrasonic cavitation.The studies of both porous silicon single layer and porous silicon microcavity(PSM)show that ultrasonic etching optimizes the sample's optical characteristics.The best quality sample has been acquired by combining the ultrasonic etching with pulsed etching.This new etching method is an efficient technique to fabricate porous silicon materials

especially PSM

and opens a feasible way to realizing the application of porous silicon materials.