Photoluminescence of InP nanocrystals embedded in silica gel-glasses as a function of temperature, and excitation power

InP nanocrystals embedded in silica glasses were prepared by combining the sol-gel process and the heat treatment in H2 gas. The size of InP nanocrystals was found to be from 2 to 8 nm in diameter by transmission electron microscopy. A strong photoluminescence (PL) with peaks at 605, 735 and 856 nm was observed from 3InP/100SiO3 nanocompositions at 77 K. The temperature- and excitation power-dependent PL spectra from the nanocomposition are measured in order to confirm the origin of the PL spectra. The behaviors of the three peaks emissions suggest that 605, 735, and 856 nm emissions do not have the same origin. The PL peak centered at 856 nm may arise from 8 nm InP nanocrystals with 5-10% size distribution instead of all the InP nanocrystals with different sizes embedded in the SiO2 gel-glasses. The 605 and 735 nm emissions may arise from oxygen related defect centers in the SiO2 gel-glass matrix and at the interface between the InP crystallite core and SiO2 glass matrix. The quenching of PL from the InP nanocrystals with diameters <8 nm may be quenched due to the pressure-induced Γ-X transition. The result provides an evidence for the prediction of Fu and Zunger.