Photoluminescence in the visible and infrared regions of the spectrum
is investigated for porous gallium arsenide prepared by the electrolyt
ic or chemical etching of GaAs. The IR luminescence band of porous GaA
s is shifted from the maximum for crystalline GaAs into the long-wavel
ength region of the spectrum and has a greater width. All the samples
are characterized by a broad emission band in the visible region; the
intensity and shape of the band depend on the layer preparation condit
ions. Two maxima are discernible in the band in the vicinity of 420 nm
and 560 nm. An explanation is given for both the visible luminescence
and the modification of the IR band of porous GaAs. It is concluded f
rom a comparison of the visible luminescence of porous GaAs with emiss
ion from hydrated oxides of arsenic and gallium that the visible-range
luminescence of porous GaAs, especially when prepared by chemical etc
hing, is determined in large measure by the presence of oxides. Consid
erations are set forth as to ways of creating quantum-size formations
on the surface of GaAs. (C) 1997 American Institute of Physics. [S1063
-7826(97)02511-8].