Comparative study of the luminescence properties of Er-, Nd- and Tm-doped Si–ZrO₂CO-sputtered films

Abstract

Er-, Nd- and Tm-doped Si-yttria stabilized zirconia (YSZ) thin film samples were prepared by rf co-sputtering. Chemical composition of the samples was determined using energy-dispersive spectroscopy (EDS) and the structure of the films by x-ray diffraction (XRD). The samples were annealed to 700 °C. Photoluminescence (PL) measurements were performed for the visible and infrared. Excitation with 457.9 nm produces spectra in the visible range due mostly to defects in the YSZ matrix with a weak Si nanoparticle surface state emission; the Tm-doped samples also present emission. Excitation with 488 nm produces spectra in the visible range with additional rare earth emissions such as the and emissions for the Er-doped samples and the emissions for the Nd-doped samples. The Er-doped samples present weak emissions and narrow emissions in the infrared range, while the Nd-doped samples present and emissions. No Tm3+ emissions in the infrared were observed. Excitation wavelength dependence measurements for the emissions show that these are due to energy transfer from the defects in the YSZ as well as from the Si nanoparticles while the same measurements for the emissions show that these are due to energy transfer from the Si nanoparticles only. Excitation flux dependence measurements for the and emissions show the sub-linear dependence characteristic of rare earth ion excitation through energy transfer from Si nanoparticles. emission dependence on emission showed that the former was possibly due to a combination of downconversion from higher levels of the Er ions, energy transfer from Si nanoparticles and upconversion transfer processes. We concluded that Er-, Nd- and Tm-doped Si-YSZ are promising materials for photonic applications, being easily broadband excited using low pumping powers.

Light-Emitting and Structural Properties of Si-rich HfO2 Thin Films Fabricated by RF Magnetron Sputtering

“…It is worth to note that PLE spectrum, measured at 720 nm detection wavelength that corresponds to PL maximum of Si-NCs emission [17], was found to be similar to PLE spectrum presented by curve 6 in Fig.5. Similar PL properties were demonstrated for the Er-doped Si-rich-ZrO 2 films [23,24]. Similar PL properties were demonstrated for the Er-doped Si-rich-ZrO 2 films [23,24].…”

“…Similar data were obtained in [22] and demonstrated that oxygen-related defects can take part in the excitation of Si nanoclusters in Si-rich-SiO 2 films. Meanwhile, it was shown that oxygen-deficient silicon centers (Si-ODCs) and oxygen interstitial defects are effective excitation paths for Er 3+ ions [23]. In this system, the achievement of Er emission under non-resonant excitation was ascribed to energy transfer from Si-ncs.…”

Luminescence of Er-doped silicon oxide–zirconia thin films

“…The other bands were observed for the FX samples as reported in Refs. [21,36], with an additional band at 800 nm due to the SiQO surface states [37] related to the Si np present in these films. Both GX and FX samples present a weakening of hostrelated emissions as the Er 3+ emissions get stronger for excitation at 488.0 nm.…”

“…The Er ions must then be excited by efficient energy transfer from the numerous defects present in G6. It was already mentioned [21,36] that the Er ions in the FX samples are excited both by the defects and by the Si np present in these films. Nonradiative energy transfer from the ZrO 2 host to RE ions has been previously reported [34,53].…”

“…4, 5, and 7. This also explains why the HX samples (Nd-doped Si-YSZ) [36] present very little emission due to energy transfer from the defects since Nd ions can only occupy sites with sevenfold coordination, in contrast with the Er ions, which can occupy sites with sixfold, sevenfold, or eightfold coordination [49], making their distribution more irregular and with a great tendency to cluster. Comparison of the Er 3+ : 4 I 11/2 -4 I 15/2 peak emission intensity with respect to the Er 3+ : 4 I 13/2 -4 I 15/2 peak emission intensity for excitation at 488.0 nm is shown for samples B5, F3, and G6 in Fig.…”