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Electrochemical deposition of PbSe nanoparticles onto n- and p-Si wafers and into nanoporous SiO2 layer on n- and p-Si single crystals (Si/SiO2) was studied. PbSe is narrow bandgap semiconductor widely used for manufacturing of photodetectors, photoresistors and IR photoemitters. PbSe deposition on the surface of Si and into nanopores in SiO2 layer on Si is of great interest from the practical point of view as silicon is the basic material for modern electronics. Different methods including MBE, thermal evaporation in vacuum, liquid-phase epitaxy, pulsed laser deposition, etc. are used for PbSe/Si heterostructures formation. The electrochemical approach possesses some advantages over the mentioned techniques: it is energy-efficient and does not require expensive equipment, provides convenient process control by the electrode potential or current. Moreover, most physical deposition methods fail to cover the inner surface of porous substrates, whereas electroplating has been successfully used for this purpose.
PbSe particles with sizes from 70 to 150 nm were cathodically deposited at ambient conditions onto n- and p-Si wafers and nanoporous Si/SiO2 template from acidic electrolyte containing Pb(II) and Se(IV) species. Nanopores in SiO2 layer were created under etching of latent tracks of 350 MeV Au+ ions in HF (w = 1.35 %). Uniform through cone-shaped nanopores with base diameters of 110 and 250 nm were formed. The level of pores filling with PbSe was controlled by deposition time. The used electrodeposition technique allowed producing templates where all the pores were uniformly filled with PbSe.
For n-Si substrate the strong effect of deposition potential on the morphology and element composition of the product was found. The mechanism of PbSe nucleation and growth onto n- and p-Si was investigated. PbSe deposition onto n-Si takes place in the dark and under illumination, while onto p-Si – only under illumination, when the photoelectrons are generated in p-Si substrate. Cathodic deposition of PbSe onto n-Si is irreversible – Shottky barrier is formed on n-Si/PbSe interfaces. Anodic oxidation of PbSe on n-Si is observed only under illumination. Being electrodeposited onto p-Si, PbSe undergoes anodic oxidation both in the dark and under illumination.
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