A pulsed anodic etching method is developed to prepare light-emitting
porous silicon. Under the same equivalent etching condition, pulsed et
ching can yield a more uniform porous silicon film with stronger photo
luminescence intensity than the film prepared by ordinary de etching.
The atomic force microscopic observation shows that the porous silicon
surface prepared by pulsed etching contains more widely separated Si
columns but with steeper sidewalls, which are believed to result in th
e improvement of quantum confinement. The thickness of pulse etched po
rous silicon film is found to be much larger than that of a de etched
sample. (C) 1996 American Institute of Physics.