Abstract
In this study, we fabricate ZnO thin films with nano-crystalline Si (nc-Si) quantum dots (QDs) using a ZnO/Si multilayer deposition structure and a post-annealing process, and the formation of high crystallinity of Si QDs embedded in the crystalline ZnO matrix is demonstrated. For optical properties, the essential features of ZnO material, high transmission in long-wavelength and high absorption in short-wavelength ranges, are preserved. We observe significantly enhanced light absorption and an unusual photoluminescence emission peak contributed from the nc-Si QDs in the middle-wavelength range. In addition, we confirm the formation of optical sub-bandgap and the obtained value is quite close to the unusual PL emission peak. We show that meaningful sub-bandgap can form in ZnO thin film by embedding nc-Si QDs while maintaining the advantageous properties of ZnO matrix. This newly developed composite material, nc-Si QD embedded ZnO thin films, can be useful for various electro-optical applications.
Highlights
Nano-crystalline silicon quantum dots (QDs) embedded in Si-based dielectric materials like SiO2 and Si3N4 had been extensively studied and integrated with various electro-optical devices, e.g. light emitting devices (LEDs) [1], transistors [2], photovoltaic (PV) cells [3], and so on
We fabricate ZnO thin films with nano-crystalline Si quantum dots (QDs) using a ZnO/Si multilayer deposition structure and a post-annealing process, and the formation of high crystallinity of Si QDs embedded in the crystalline ZnO matrix is demonstrated
We observe significantly enhanced light absorption and an unusual photoluminescence emission peak contributed from the nano-crystalline Si (nc-Si) QDs in the middle-wavelength range
Summary
Nano-crystalline silicon (nc-Si) quantum dots (QDs) embedded in Si-based dielectric materials like SiO2 and Si3N4 had been extensively studied and integrated with various electro-optical devices, e.g. light emitting devices (LEDs) [1], transistors [2], photovoltaic (PV) cells [3], and so on. They exhibit the feasibility and show great potential for devices integrating nc-Si QDs. In this work, we embed nc-Si QDs into ZnO thin films because ZnO has many desirable features to function as nc-Si QDs’ matrix material, such as wide and direct bandgap, high transparency, and highly tunable electrical properties [4]. The nano-structural, crystalline, and optical properties of ZnO thin films with nc-Si QDs are investigated and discussed
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