Optical properties and sub-bandgap formation of nano-crystalline Si quantum dots embedded ZnO thin film

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.

Direct bandgap materials based on the thin films of Se x Te100 − x nanoparticles

“…In the last two decades, much research work is focused on the synthesis and characterization of semiconducting nanomaterials [1]. Among these nanostructures, nanochalcogenides are important materials for various applications such as nanoelectronic devices, nanomemory devices, optical memory devices, etc.…”

Interface State Luminescence and Sub‐Bandgap Absorption Based on CuGaO2 Nanoplates/ZnO Nanowires Heterostructure Arrays

“…After being assembled by the dense vertical ZnO NWs arrays, the treated CGO NPs appears a red shift in the absorption spectrum compared with pure CGO NPs. This phenomenon could be attributed to the sub‐bandgap absorption effect, and the origin of this effect was caused by the build‐in electric field which established through the diffusion of carriers between the p–n junction . The schematic diagram of sub‐bandgap absorption are illustrated in inset of Figure , and the two‐step moving process of electron would take place.…”

Improvement of optical transmittance and electrical properties for the Si quantum dot-embedded ZnO thin film

“…Hence, ZnO can serve as the Si QDs’ matrix to achieve bandgap engineering, reduce the optical loss from the matrix’s absorption, and efficiently enhance the carrier transport efficiency for optoelectronic device application. The fabrication and fundamental optical properties of the Si QD-embedded ZnO thin films have been reported in our previous works [12,13]. In this study, improvement of optical transmittance and electrical properties of the Si QD-embedded ZnO thin films is investigated and discussed.…”