Our scientists have discovered a method that enables efficient emission of photons from quantum superlattices in the red, green and ultraviolet wavelength ranges. This finding is crucial for potential applications in semiconductor light-emitting diodes, such as near-white electroluminescent LEDs.

Quantum superlattices are advanced structures consisting of alternating layers of two or more different materials of nanoscale thickness (typically, several nanometres per layer) which have numerous applications in optoelectronics. Our scientists have discovered that precise placement of europium ions within ZnCdO quantum wells during the growth of {ZnCdO/ZnMgO} superlattices enables efficient emission of photons from these structures in the red, green and ultraviolet spectral ranges. This observation is crucial for the potential application of oxide structures in semiconductor light-emitting diodes, such as near-white electroluminescent LEDs. Operation of the latter is based on one of the basic principles of colorimetry, i.e. additive mixing of the primary colours of light. We can obtain white light by mixing red, green and blue components. In the case of our selectively Eu-doped {ZnCdO/ZnMgO} superlattices we can tune the emitted colour towards white light.

In our article written in collaboration with scientists from Portugal, published in Nanoscale vol. 17, p. 7055 (2025), we described the process of growing quantum superlattices based on oxide materials and we presented their detailed structural and optical characteristics. We showed that the advanced growth technique of molecular-beam epitaxy allows us to closely control the thickness of individual layers in superlattices and to precisely place europium ions within their the quantum wells. Meticulous optimization of growth parameters and in-depth characterization of these complex structures are crucial for developing semiconductor circuits for future applications in optoelectronics. In our case they allowed us to achieve efficient light emission in three different colour ranges from a single quantum structure.

The significance of our results was acknowledged by the editor of Nanoscale, who selected an article-related graphic for the journal cover.