Phenomenon logical investigation of size dependent Photo lumine science from silicon Nano structures

Abstract

Theobservation of visible luminescence with finite quantum efficiency at room temperature fromnanoporoussilicon(nP-Si)promptedrenewedhopeforthepos sible integration of Silicon (Si) based light emitting devices. Since then, nP-Si quan tum wires research has attracted considerable attention. However, the origin of photo luminescence (PL) and the blue shift in PL peak is still a debatable issue. We present a phenomenological model formulation to explain PL spectra from np-Si with diameters of wires ranging from 1-6 nm based on the quantum confinement model. We explicitly calculate the expression for PL spectra as a function of en ergy up shift. And we take the size distribution of nano porous Si quantum wires as Gaussian. To validate our model wecompareoursimulatedPLspectrawithexperi ments. To observe the nature of blue shift further we use the energy gap vs. diame ter as an input parameter from pseudo potential simulation and tight binding fit to our model and generate PL that shows the same nature as experimental one. Our results clearly show the blue shift of PL as a function of energy up shift and wave length by vary- ing the diameter of wires. We believe that Gaussian model looking at PL of nP-Si quantum wires is new observation that provide very good qualitative agreement with other observations.