Formation and characterization of CdS/methyl-grafted porous silicon junctions

The incorporation of cadmium sulfide into fresh and methyl-grafted porous silicon layers is investigated. Methyl grafting is obtained by an electrochemical method. Cadmium sulfide deposition is achieved by using a sequential chemical bath deposition. Characterizations of the resulting structures by infrared spectroscopy, transmission electron microscopy and photoluminescence measurements are presented. They show that in the case of fresh porous layers, the CdS deposition process is accompanied with some oxidation of the porous material, leading to severe degradation of the luminescence properties. Such degradation is drastically reduced in the case of methyl-grafted layer.