Study of band-edge emission in CdS layers grown on |p-type porous GaAs substrates

We present the optical properties of sulphide cadmium (CdS) deposited, by vacuum evaporation technique, on porous p-type GaAs substrates with different porosities and compared to that deposited on glass and nominal p-type GaAs substrates. The CdS layer deposited on glass substrate exhibit average transmittance about 62% in the visible region and very sharp absorption edge at 495 nm. The room temperature band gap energy calculated from the transmittance spectra is about 2.5 eV. The surface roughness (rms) has been determined by atomic force microscopy (AFM). The photoluminescence (PL) and reflectance spectroscopy of the samples before and after deposition of CdS were measured to study the effect of the porosity on the luminescence properties of CdS/porous GaAs heterostructures.