Surface control of CdSe nanocrystals by UV-exposure in air and successive thermal treatment under ultra high vacuum

Hyun Ju Choi, Seok Joo Wang, Hyuncheol Kim, Hyung Ho Park, Ho Jung Chang, Hyeongtag Jeon

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Colloidal CdSe nanocrystals were synthesized through a solution process. The CdSe nanocrystals coated on Si(1 0 0) wafers were UV-exposed in either an air or argon atmosphere to distinguish the effect of generated ozone from UV-radiation at 365 nm on the removal of surface capping pyridine molecules. The pyridine on the CdSe nanocrystal's surface could be effectively removed by the ozone generated during UV-exposure with an accompanying highly oxidized surface state of the CdSe nanocrystals. For the removal of surface oxides of CdSe nanocrystals, a successive thermal treatment under ultra high vacuum (UHV) was adopted. The optical energy bandgap measured by using UV-vis absorption spectroscopy showed a red shift with treatment with an increase of annealing temperature. The electronic energy structure of UHV-annealed CdSe nanocrystals film was analyzed in situ using X-ray absorption and photoelectron spectroscopy. A great resemblance was found between the values of the optical and electron energy bandgaps of effectively surface-treated CdSe nanocrystals film after UHV-annealing at 400 °C.

Original languageEnglish
Pages (from-to)6886-6889
Number of pages4
JournalApplied Surface Science
Issue number21
Publication statusPublished - 2008 Aug 30



  • CdSe nanocrystals
  • Electronic structure
  • Thermal treatment
  • UV treatment

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