Quantum Characterization of Si Nano-Particles Fabricated by Multi-Hollow Discharge Plasma Chemical Vapor Deposition

Si is currently the most widely used material in the photovoltaics. Since the first development of Si photovoltaics, various types of Si solar cells, such as single-crystal and multicrystalline, amorphous and thin film, have been developed and commercialized. The present work focused on Si quantum dots as another route to Si photovoltaics. To apply Si quantum dots to photovoltaic devices, the quantum characteristics of Si nanoparticles should be verified, and so 4 nm crystalline Si nano-particles were fabricated by multi-hollow discharge plasma chemical vapor deposition. The size and distribution of these particles were determined by transmission electron microscopy and compared against theoretically calculated values. These particles were applied to the fabrication of a Schottky cell and the quantum efficiency of the Si quantum dot layer was measured as a function of the incident photon energy. The quantum efficiency was found to exceed 100% and so multiple exciton generation from the Si quantum dots was clearly realized.