Abstract
Atomic scale control of the thickness of thin film makes atomic layer deposition highly advantageous in the preparation of high quality super-lattices. However, precisely controlling the film chemical stoichiometry is very challenging. In this study, we deposited SiOx film with different stoichiometry by plasma enhanced atomic layer deposition. After reviewing various deposition parameters like temperature, precursor pulse time, and gas flow, the silicon dioxides of stoichiometric (SiO2) and non-stoichiometric (SiO1.8 and SiO1.6) were successfully fabricated. X-ray photo-electron spectroscopy was first employed to analyze the element content and chemical bonding energy of these films. Then the morphology, structure, composition, and optical characteristics of SiOx film were systematically studied through atomic force microscope, transmission electron microscopy, X-ray reflection, and spectroscopic ellipsometry. The experimental results indicate that both the mass density and refractive index of SiO1.8 and SiO1.6 are less than SiO2 film. The energy band-gap is approved by spectroscopic ellipsometry data and X-ray photo-electron spectroscopy O 1s analysis. The results demonstrate that the energy band-gap decreases as the oxygen concentration decreases in SiOx film. After we obtained the Si-rich silicon oxide film deposition, the SiO1.6/SiO2 super-lattices was fabricated and its photoluminescence (PL) property was characterized by PL spectra. The weak PL intensity gives us greater awareness that more research is needed in order to decrease the x of SiOx film to a larger extent through further optimizing plasma-enhanced atomic layer deposition processes, and hence improve the photoluminescence properties of SiOx/SiO2 super-lattices.
Highlights
Compatible with common micro-electronic device fabrication techniques and materials [1,2], silicon (Si) based micro-nano devices have become the most promising material for advanced integratedNanomaterials 2019, 9, 55; doi:10.3390/nano9010055 www.mdpi.com/journal/nanomaterialsNanomaterials 2019, 9, 55 opto-electronic technologies in the future [3]
To examine the properties of Si rich SiOx obtained by Atomic layer deposition (ALD) in this study, SiO1.6 /SiO2 superlattice was fabricated and its photoluminescence property was characterized by PL spectra
In order to optimize the growth parameters needed for the self-limiting deposition of SiOx thin film, the effect of temperature, TDMAS dose, and O2 plasma duration was studied
Summary
Compatible with common micro-electronic device fabrication techniques and materials [1,2], silicon (Si) based micro-nano devices have become the most promising material for advanced integrated. Control over all three parameters (size, density, spherical shape) can be reached by depositing thin alternating layers of stoichiometric and Si rich dielectrics in the form of a superlattice (SL). This approach has been well established for silicon nanocrystals in SiO2 matrix. Atomic layer deposition (ALD) is a promising technology for advanced thin film deposition as it offers excellent control at the atomic scale over the thickness and uniformity of the film [25,26,27] It allows the precise preparation of size- and distribution-controlled silicon nanocrystals. To examine the properties of Si rich SiOx obtained by ALD in this study, SiO1.6 /SiO2 superlattice was fabricated and its photoluminescence property was characterized by PL spectra
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