Photoluminescence and local electric fields in two-dimensional structures of macroporous silicon with CdS nanocoatings (In Ukrainian)

The influence of local electric fields in two-dimensional structures of macroporous silicon with CdS nanocrystals on the reduction of nonradiative recombination in light-emitting elements based on the system «macroporous silicon – nanocoating» was determined. Colloidal nanoparticles of cadmium sulfide in aqueous and alcoholic polyethyleneimine media were used to manufacture effective light-emitting elements based on macroporous silicon structures with nanocoatings. It was found that for pre-purified oxidized structures of macroporous silicon with nanocoatings of CdS nanoparticles, resonant electron scattering with 1Е turns into ordinary electron scattering by ionized impurities with 2E3/2. The intensity of the local electric field at the boundary «Si–SiO2–CdS nanocoating» was determined by IR absorption oscillations (width of Vanier-Stark steps). The mechanism of Si-SiO2 in the structures of oxidized silicon with surface nanocrystals of CdS was studied by the methods of electroreflection (direct band-band transition) and photoconductivity (indirect band-band transition). Oxidized structures of macroporous silicon with optimal depth of macropores and coating of CdS nanoparticles to ensure a large emitting surface area were investigated for the production of efficient light-emitting elements. For macroporous silicon structures with a nanocoating of CdS nanoparticles in polyethyleneimine with an oxide thickness of 10–20 nm and an optimal macropore depth of 70-120 μm, an increase in IR absorption and oscillation amplitude was measured. For this range of oxide thickness and depth of macropores, the maximum value of photoluminescence intensity was also obtained. Photoluminescence quantum yield was measured for CdS nanocoated macroporous silicon structures purified by oxidation and ultrasonic treatment.