Effect of Amorphous Si Quantum-Dot Size on 1.54 μm Luminescence of Er

Abstract

The role of the size of amorphous silicon quantum dots in the Er luminescence at 1.54 m was investigated. As the dot size was increased, more Er ions were located near one dot due to its large surface area and more Er ions interacted with other ones. This Er-Er interaction caused a weak photoluminescence intensity, despite the increase in the effective excitation cross section. The critical dot size needed to take advantage of the positive effect on Er luminescence is considered to be about 2.0 nm, below which a small dot is very effective in the efficient luminescence of Er. . = 0, respectively. is the decay time. The decrease in decay value with increasing dot size indicates that the nonradiative process is z

Direct Optical Energy Gap in Amorphous Silicon Quantum Dots

“…The absorption spectrum of a-SiQDs consists of a series of discrete lines as indicated in Figure 2. The con- fining electrons in a-SiQD produce a series of even sharper spikes which corresponds to a series of confinement quantum levels for these electrons, where the quantum dots absorb all wavelengths shorter than the absorption maximum (~E g ) [38]. Also, it is noted that the threshold of absorption is shifted by several electron volts from that of the bulk.…”

Size Effects in Amorphous Nanosolids

“…One of the most important areas of practical application where property relates itself with size of amorphous nanosolids is luminescence. This conception is supported by both theoretical [90][91][92] and experimental [93][94][95] studies. Some examples of photoluminescence in amorphous nano silicon, the most studied substance in this context are discussed below.…”

“…A family of materials that occupies an important position in the above domain includes nanosized amorphous silicon, designated a-Si, and a-Si:H where hydrogen ions passivate the surface of the particle (taking care of the dangling bonds [5]), as also the group that is doped with various concentrations of erbium [93,96] (see below). Additional examples of dopants include carbon [97] and lithium [98].…”

“…The erbium ion (Er 3+ ) is in essence the major dopant for development of luminescent a-Si; the main photoluminescence (PL) band is observed at 1.54 μm -intra-4f shell excited state-to-ground-state transition: ( 4 I 13/2 → ( 4 I 15/2 ). [114] for all such optical materials [4,93,96,115]. The choice behind the selection of the rare earth ion looks forward to possible application as LED's and laser systems that function at around 1.54 μm [93,96], and the extensive work [4,93,96,115] on Er-doped a-Si is based on the advantages over crystalline Si [96] The common configuration is Er-doped a-Si quantum dots (QD) in silicon nitride films.…”

“…[114] for all such optical materials [4,93,96,115]. The choice behind the selection of the rare earth ion looks forward to possible application as LED's and laser systems that function at around 1.54 μm [93,96], and the extensive work [4,93,96,115] on Er-doped a-Si is based on the advantages over crystalline Si [96] The common configuration is Er-doped a-Si quantum dots (QD) in silicon nitride films. An additional (restricted) dopant can be oxygen, used for reduction of luminescence quenching [96].…”