Abstract
Photonic crystal modes can be tailored for increasing light matter interactions and light extraction efficiencies. These PhC properties have been explored for improving the device performance of LEDs, solar cells and precision biosensors. Tuning the extended band structure of 2D PhC provides a means for increasing light extraction throughout a planar device. This requires careful design and fabrication of PhC with a desirable mode structure overlapping with the spectral region of emission. We show a method for predicting and maximizing light extraction from 2D photonic crystal slabs, exemplified by maximizing silicon photoluminescence (PL). Systematically varying the lattice constant and filling factor, we predict the increases in PL intensity from band structure calculations and confirm predictions in micro-PL experiments. With the near optimal design parameters of PhC, we demonstrate more than 500-fold increase in PL intensity, measured near band edge of silicon at room temperature, an enhancement by an order of magnitude more than what has been reported.
Highlights
Periodic structuring of optical materials such as photonic crystal (PhC) slabs, can impart geometric control over optical modes[1,2]
With near optimal design parameters for the PhCs, we demonstrate a greater than 500-fold increase in PL intensity measured near the band edge of silicon at room temperature, an enhancement by an order of magnitude in respect to what has been previously reported in similar PhC structures with air holes[16,17] Other studies of defect-free Si PhC slabs consist of nanorods or nanobox, have reached up to 122-fold increase in PL intensity over that of an un-patterned substrate
In order to identify the origin of this enhancement, the PhC band structure is calculated by means of 3D Finite Difference Time Domain (FDTD, Lumerical) simulation displayed in Fig. 1d, scaled by normalized frequency a/λ, where λ is wavelength
Summary
Crystal Slabs received: 18 January 2016 accepted: 12 April 2016 Published: 26 April 2016. Efficient light emission results from the excitation of only a small, nanoscale area of the device, and fabricating high quality nano-cavities remains a formidable challenge[15] Instead, tuning the extended band-structure of 2D PhCs provides another means for increasing PL intensity throughout a planar device. This requires careful design and fabrication of PhCs, with a desirable mode structure overlaps with the spectral region of PL emission. The quantity of radiation modes at electronic band edge are thereby identified as an important factor contributing to the enhancement of light extraction in indirect bandgap semiconductors[16,17,18,19] as well as direct bandgap ones[20,21]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
