On the Photoluminescence Theory in Nanocrystalline Silicon: A New Improvement

Silicon has long been the foundational semiconductor material for a broad range of electronic devices, owing to its numerous advantages: wide natural availability, ease of synthesis in both crystalline and amorphous forms, and relatively low production cost. However, despite these benefits, silicon is inherently limited in the field of optoelectronics due to its indirect bandgap, which results in low quantum efficiency for light emission, typically in the infrared region. One promising strategy to address this limitation is the development of nanocrystalline silicon, which consists of low-dimensional nanostructures such as quantum wires (QWs) and quantum dots (QDs). These structures exhibit enhanced photoluminescence and electroluminescence, primarily due to quantum confinement of excitons within the conduction and valence bands, leading to significantly improved quantum efficiency. Although research into these processes has spanned several decades, a definitive consensus on the mechanisms underlying photoluminescent emission in nanocrystalline silicon remains elusive. This work reviews two leading theoretical models proposed to explain this phenomenon and introduces a new, more comprehensive model that may provide a deeper and more accurate understanding of photoluminescence in nanocrystalline silicon. The new theory is applied in a case study.