Research Paper

Journal of Nanoparticle Research

, Volume 11, Issue 3, pp 569-574

Surface effects on the photoluminescence of Si quantum dots

  • Chiang-Jing WangAffiliated withDepartment of Materials Science and Engineering, National Tsing Hua University
  • , Meng-Yen TsaiAffiliated withDepartment of Materials Science and Engineering, National Tsing Hua University
  • , Cheng Chung ChiAffiliated withDepartment of Physics, National Tsing Hua University
  • , Tsong-Pyng PerngAffiliated withDepartment of Materials Science and Engineering, National Tsing Hua UniversityDepartment of Chemical Engineering and Materials Science, Yuan Ze University Email author 

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Abstract

Si quantum dots (SiQDs) with sizes ranging from 5 to 20 nm were fabricated by vapor condensation. They showed red photoluminescence (PL) in vacuum with the peak located at around 750 nm. After the specimen was exposed to air, the PL intensity became higher, and continued to increase during the PL test with a cycling of vacuum-air-vacuum. In pure oxygen, the PL intensity exhibited an irreversible decrease, while in nitrogen a smaller amount of reversible increase of PL intensity was observed. Furthermore, the PL intensity exhibited a remarkable enhancement if the SiQDs were treated with water. With HF treatment, the PL peak position showed a blue-shift to 680 nm, and was recovered after subsequent exposure to air. Si–O–H complexes were suggested to be responsible for this red luminescence. The irreversible decrease of PL intensity due to oxygen adsorption was speculated to be caused by the modification of chemical bonds on the surface. In the case of nitrogen adsorption, the PL change was attributed to the surface charging during adsorption.

Keywords

Si Quantum dots Photoluminescence Si–O–H complexes Effects of ambient gases Synthesis Oxygen adsorption