Photoluminescence of Sequential Infiltration Synthesized ZnO nanostructures

摘要

For the past several years there have been ongoing efforts to incorporate zinc oxide (ZnO) inside polymethyl methacrylate (PMMA), in the form of nanoparticles or quantum dots, to combine their optical properties for multiple applications. We have investigated a variation of atomic layer deposition (ALD), called sequential infiltration synthesis (SiS), as an alternate method to incorporate ZnO and other oxides inside the polymer. PMMA is a well-known ebeam resist. We can expose and develop patterns useful for photonics or sensing applications first, and then convert them afterwards into a hybrid oxide material with enhanced photonic, or sensing, properties. This is much easier than micromachining films of ZnO or other similar oxides because they are difficult to etch. The amount of ZnO formed inside the polymer film is magnitudes higher than equivalent amount deposited on a flat 2D surface, and the intensity of the photoemission suggests there is an enhancement created by the polymer-ZnO interaction. Photoemission from thin films exhibit photoemission similar to intrinsic ZnO with oxygen vacancies. These vacancies can be removed by annealing the sample at 500 ℃ in an oxygen rich environment. SiS ZnO exhibits unusual photoemission properties for thick polymer films, emitting at excitations wavelengths not found in bulk or standard ZnO. Finally we have shown that patterning the polymer and then doing SiS ZnO treatment afterwards allows modifying or manipulating the photoemission spectra. This opens the doors to novel photonic applications.