Effect of Surface Plasmon Resonance on the Photoluminescence from Si Quantum Dot Structures for Third Generation Solar Cell Applications

ABSTRACTLow dimensional structures like quantum dots (QDs) offers the the ability to tune the absorption properties of standard semiconductor materials. However, QDs are relatively weak light absorbers and hence may benefit significantly from coupling with plasmonic modes in nearby metal structures. In the case of a Si QD absorber layer for photovoltaic applications, enhanced absorption would lead to improved power conversion efficiency. Silver metal nanoparticles (MNPs) were deposited on Si QD structures using the self-assembly method of evaporation and annealing. Room temperature photoluminescence (PL) measurements were used to study the surface plasmon (SP) enhanced emission from the samples. The results were compared to conventional metal back reflectors. Enhanced surface plasmon coupled emission (SPCE) from Si QDs in the vicinity of silver metal nanoparticles (MNPs) is observed with a good correlation between the enhancement and the resonance excitation. Quenching was observed from the same emitter layers placed in close proximity to thin flat silver reflector layers, indicating the importance of the spacer layer between a metal layer and the quantum dots in optimising enhancement. The results have implications for the design of SP-enhanced QD solar cells.