Oxidation and photoluminescence of ErSi 2 nanowires formed on Si substrates

Abstract

The ErSi 2 nanowires were formed on Si(1 1 0) substrate by a self-assembly process. The wires were highly parallel and grew along the Si〈1 1 0〉 direction. For size controlling of the wires, the deposited layer thickness of Er and the annealing temperature were changed. It was revealed that the annealing temperature is more important for reducing the wire width. The ErSi 2 nanowires were epitaxially grown on Si substrates and had smooth surface originally. It became rough after oxidizing in air. Furthermore, the crystal phase of ErSi 2 turned into amorphous due to the oxidation. The originally grown ErSi 2 wires, did not give rise to light emission. In contrast, an emission peak at wavelength around 1.5 μm was observed from the oxidized samples, indicating the Er–Si–O compound formation. Sharp photoluminescence peaks related to inner core transitions of Er 3+ ions were observed from the oxidized samples synthesized at high temperatures.