| Abstract
| - A mildchemical oxidation reaction for luminescent nanocrystalline poroussilicon has been developed. The reaction involves treatment of thematerial with dimethyl sulfoxide (DMSO) at room temperature. TheDMSO delivers an O atom to the silicon surface, generating a defectiveoxide layer that quenches the photoluminescence. The defects canbe passivated, and photoluminescence is preserved if radical traps areadded to the reaction mixture duringoxidation.
- Dimethyl sulfoxide acts as a mild room-temperature oxidant ofluminescent porous silicon. The oxidation reactionis accompanied by a loss in photoluminescence intensity from thesilicon nanocrystallites, indicating that theoxide formed under these conditions is electronically defective.The rate of oxidation is reduced if the reactionis carried out in the presence of the radical traps2,6-di-tert-butyl-4-methylphenol (butylatedhydroxytoluene,BHT) or cumene. In addition, photoluminescence intensity ispreserved if the DMSO oxidation reaction is carriedout in the presence of high concentrations of BHT. The BHT isproposed to form a more electronically passiveoxide layer by hydrogenating the surface radicals (dangling bonds)generated during the oxidation reaction.
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