Fabrication and optical properties of two-dimensional photonic crystals of CdSe pillars

Abstract

The combination of electron beam lithography and electrochemical deposition has been employed to fabricate well-controlled submicrometer-scale CdSe pillars. The formation of the wurtzite crystal structure of CdSe pillars has been confirmed by x-ray diffraction and Raman spectra. Quite interestingly, we found that the intensity of micro-photoluminescence can be greatly enhanced at the specially designed two-dimensional photonic crystals (PCs) based on Maxwell’s equations. This peculiar phenomenon can be explained quite well in terms of the effects of PCs. PCs can provide a photonic bandgap for the emission in the lateral dimensions so that the emission of CdSe pillars cannot propagate in the lateral plane and can only propagate upward with respect to PCs. Besides, PCs can also provide a pathway for the phase match between guided modes and radiation modes to avoid total internal reflection. Thus, the detected PL intensity normal to the lateral plane can be greatly enhanced.