Myung M. Sung

Effect of the extinction coefficient on the extraction efficiency of ZnS:Mn thin-film phosphors grown on two-dimensional nanorod substrates

We have studied the effects of varying the extinction coefficient of two-dimensional (2D) nanorod-assisted ZnS:Mn thin-film phosphors on their photoluminescence extraction efficiency. The finite-difference time-domain method was employed for the design and analysis of 2D nanorod-assisted thin-film phosphors. Using a nanorod pattern with a depth of 200 nm, a lattice constant of 600 nm, and a radius of 180 nm, the extraction efficiency of a transparent ZnS:Mn thin-film phosphor is predicted theoretically to increase by a factor of more than ∼9.1. Experiments have shown that incorporation of the 2D SiO2 nanorod layer only improves the light extraction efficiency over that of a conventional ZnS:Mn thin-film phosphor by a factor of ∼4.0. We discuss the reasons for this mismatch between the theoretical and experimental extraction efficiencies, in order to further improve the extraction efficiency of ZnS-based thin-film phosphors.

Hydrogen elimination reactions in the thermal decomposition of alcohols on Si(100) surfaces

The thermal decomposition of 1-pentanol and 2-methyl-1-butanol on clean Si(100)-2×1 in an ultrahigh vacuum has been examined using temperature programmed desorption, intergrated desorption mass spectrometry, and low-energy electron diffraction. The results show that the alkoxy species formed on Si(100) are stable up to temperatures of about 480 K. Above 500 K, the alkoxy species decompose on Si(100) via the γ-hydrogen elimination mechanism to yield alkene in the gas phase, together with adsorbed hydrogen. The H2 gas is evolved by the recombinative desorption of hydrogen atoms that are generated by the adsorption of alcohols and/or the decomposition of alkoxy species. The H2 thermal desorption exhibits a peak near 800 K, which indicates that the H2 gas is evolved from the monohydride phase on Si(100).