Abstract
A Si quantum dot (QD)-embedded ZnO thin film is successfully fabricated on a p-type Si substrate using a ZnO/Si multilayer structure. Its optical transmittance is largely improved when increasing the annealing temperature, owing to the phase transformation from amorphous to nanocrystalline Si QDs embedded in the ZnO matrix. The sample annealed at 700°C exhibits not only high optical transmittance in the long-wavelength range but also better electrical properties including low resistivity, small turn-on voltage, and high rectification ratio. By using ZnO as the QDs’ matrix, the carrier transport is dominated by the multistep tunneling mechanism, the same as in a n-ZnO/p-Si heterojunction diode, which clearly differs from that using the traditional matrix materials. Hence, the carriers transport mainly in the ZnO matrix, not through the Si QDs. The unusual transport mechanism using ZnO as matrix promises the great potential for optoelectronic devices integrating Si QDs.
Highlights
Si quantum dots (QDs) embedded in traditional Si-based dielectric matrix materials like SiO2 and Si3N4 have been extensively studied and successfully applied to various optoelectronic devices [1,2,3], owing to their many unique characteristics such as highly tunable bandgap and better optical properties [4,5,6]
In our previous works, we demonstrated that a high Si sputtering power can assist the formation of the selfaggregated amorphous Si QDs embedded in the ZnO matrix during deposition by utilizing a ZnO/Si ML structure [12]
This indicates that a higher Tann can largely enhance the crystalline quality of Si QDs embedded in the ZnO matrix
Summary
Si quantum dots (QDs) embedded in traditional Si-based dielectric matrix materials like SiO2 and Si3N4 have been extensively studied and successfully applied to various optoelectronic devices [1,2,3], owing to their many unique characteristics such as highly tunable bandgap and better optical properties [4,5,6]. To further improve the device performance, utilization of Si-rich Si-based dielectric materials as Si QDs’ matrices has been developed [9,10]. We propose to embed Si QDs into a ZnO thin film because ZnO has many desirable features to function as Si QDs’ matrix material, e.g., wide and direct bandgap, high transparency, and highly tunable electrical properties [11]. ZnO can serve as the Si QDs’ matrix to achieve bandgap engineering,
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