Electron-beam-induced formation and spectral control of CdSe quantum dots for green–yellow emission

Direct laser emission in the green–yellow spectral range remains a major challenge in semiconductor laser development due to material limitations. This study explores the formation dynamics and optical characteristics of CdSe quantum dots (QDs) induced by electron-beam irradiation as a strategy to bridge this spectral gap. Time-resolved diffraction analysis reveals that QD nucleation initiates rapidly within one minute of irradiation, with the formation rate strongly influenced by beam intensity. Spatially resolved photoluminescence (PL) and transmission electron microscopy measurements show distinct growth behaviors: enhanced Cd diffusion at the center of irradiated regions leads to smaller QDs and blueshifted emission, while Cd accumulation at the edges promotes larger QDs and redshifted emission. Under saturated irradiation conditions, the PL peak wavelength stabilizes within the 573–581 nm range, independent of initial CdSe thickness, indicating a self-regulating atomic rearrangement process. This convergence highlights the robustness of the electron-beam-induced QD formation mechanism, which enables wavelength-specific control over emission properties. The ability to engineer QDs with emission wavelengths spanning the green–yellow range demonstrates the potential of this approach for realizing compact, multi-wavelength optoelectronic devices. These findings establish electron-beam irradiation as a versatile tool for precise nanostructure engineering and spectral tuning in advanced photonic applications.