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.

Semiconductor quantum dots for photoluminescence-based gas sensing

“…The intensifi cation of QD PL by AAO is explained by the surface scattering effects of the porous AAO redistributing high intensity electromagnetic near-fi elds for enhanced excitation of the QDs, and likewise for promoting the enhanced collection of the QD emission. 11,49,50 The optical properties can be further improved by manipulating the surface coating on the underlying Si support via refl ection and interference. For example, a Au-coated Si support further enhanced the PL by a factor of 1.5, leading to an overall enhancement by a factor of 12.6 relative to the control sample (curves 5 and 1), and owing to the high refl ectivity of the noble metal at the QD emission wavelength.…”

“…These effects were attributed to the submicron pore arrays that dictate the light-matter interaction with a limited or reduced susceptibility to analyte absorption. 11,49,50 Furthermore, a larger PL response to 10 ppm xylenes in air has been achieved from CdSe QDs dispersed on anodic aluminum oxide (AAO) supported on Au-coated Si, suggesting that a detection limit down to hundreds of ppb of xylenes is quite possible. The reliability issues have been addressed through the use of high quality CdSe/ZnS core/shell QDs assembled on AAO, which have shown the sensitive detection of hydrocarbons over an almost nine-month period, and thus are very promising for future applications.…”

Temperature and pH influences on the structural and the emission properties of electrodeposited CdSe nanowires

“…For several years, many research groups have focused on semiconductor materials in the nanoscale range to develop new electronic, optical, and biological devices [1][2][3]. To realize such devices, the cadmium selenite (CdSe), an important II-VI semiconducting compound with a direct band gap of around 1.7 eV, seems to be a very interesting candidate.…”

Engineering the refractive index of three-dimensional photonic crystals through multilayer deposition of CdS films

“…The coating can be performed at room conditions and it is extremely inexpensive; it works at moderate temperature with no need of controlled atmosphere and/or high-vacuum systems [34]. Furthermore, the possibility to perform the protocol on non-conductive substrates (Ormocer® is an organic-inorganic hybrid) gives further advantage compared to electro-chemical techniques [31]. The overall protocol is cheap, fast and highly reproducible.…”