Quantum Confinement Effects in Semiconductor Nanoparticles: A Solid-State Physics Perspective

Abstract

Semiconductor nanoparticles exhibit remarkable optical and electronic properties due to the phenomenon of quantum confinement. When the particle size approaches or becomes smaller than the exciton Bohr radius, the continuous energy bands of bulk semiconductors transform into discrete energy levels. This study investigates the quantum confinement effect in semiconductor nanoparticles using theoretical modeling based on the effective mass approximation and the Brus equation. Nanoparticle sizes ranging from 2–10 nm was analyzed to evaluate variations in band gap energy and optical absorption characteristics. The results demonstrate a strong inverse relationship between particle size and band gap energy. As particle diameter decreases, the band gap widens due to increased confinement of charge carriers. The simulated results reveal that CdSe nanoparticles with a diameter of 2 nm exhibit band gaps approaching 2.8 eV compared to the bulk value of 1.74 eV. These findings highlight the tenability of optical properties in semiconductor nanostructures and their importance for applications in optoelectronics, photovoltaics, and quantum devices.