Formation and photoluminescence characteristics of Er-related nanostructures on Si(0 0 1) substrate covered with an ultrathin SiO2 film

Er-related nanostructures self-assembled on the Si(0 0 1) covered with an ultrathin SiO2 layer have been studied by scanning tunneling microscopy and photoluminescence (PL), compared with Er-related nanostructures formed on clean Si(0 0 1). The post-annealing temperature of 560 °C-660 °C can lead to the formation of Er silicate nanobunches, with an ultrahigh density of 1 × 1012-1 × 1013 cm−2. The Er silicide nanowires are obtained at the post-annealing temperature above 700 °C. Er-related nanostructures will change from the amorphous nanobunches to the crystalline nanowires with the increase of post-annealing temperature due to the SiO desorption. The PL band shape and intensity depend strongly upon the preparation conditions and a wide band is exhibited from 1.3 μm to 1.6 μm due to defect related luminescence (D bands) and Er3+ ion. A dominant peak at 0.80 eV is observed for the nanobunches. We have distinguished the Er3+ line from the D1 line, which have the same energy region around 0.80 eV, and it is shown that our samples have effective optically-active Er3+ ions.