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.
