 | Enhancement of PL intensity of surface oxidized nanocrystalline silicon dots
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| | Kenta ARAI1), Jyunichi OMACHI1) and Shunri ODA1) |
| | 1) Research Center for Quantum Effect Electronics, Tokyo Institute of Technology |
| | The visible light emission from Si nanostructures has been a subject of focused studies since a decade ago, which will open a door to future devices such as Si-based LEDs and lasers. Although the photoluminescence (PL) of the Si nanostructures is strong enough to be seen by naked eyes, luminescence efficiency of the Si nanostructures is low compared to that of the direct gap semiconductors because of the indirect gap of Si. When the diameter of the nanocrystalline silicon (nc-Si) dot core is less than an exciton Bohr radius of Si of ∼4.9 nm, the exciton can no longer exist and an electron-hole pair is generated instead of the exciton. Within the framework of the effective mass model, no-phonon transition will rise when the size of the nanostructure is small enough due to the increase of the overlap integral between the electron envelope function and the hole envelope function [1]. By employing oxidation, the nc-Si dot core with a diameter of sub-5 nm has been achieved [2]. In this study, we demonstrate, for the first time, the enhancement of the PL intensity of the nc-Si dots due to the no-phonon transition with decreasing the diameter of the Si core by oxidation. |
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