Photoluminescence of Si/SiO₂, RE₂O₃/Si/SiO₂and RE₂O₃/Si/Al₂O₃(RE = Er, Nd, Tm) Sputtered Thin Films

Abstract

Si/SiO2, RE2O3/Si/SiO2 and RE2O3/Si/Al2O3 films were sputtered. Si/SiO2 films were annealed to 1100°C for 30 min in Ar. RE2O3/Si/SiO2 films were annealed to 700°C, 1000°C, or 1100°C for 30 min in Ar. RE2O3/Si/Al2O3 films were annealed to 700°C for 30 min in Ar. Raman spectra and photoluminescence (PL) obtained for the Si/SiO2 films show relation between Si nanocrystal (nc) presence, Si nanoparticle (np) PL and Si target area. Nd2O3 co-sputtered films presented PL for the (4F5/2, 2H9/2) → 4I9/2, 4F3/2 → 4I9/2, 4F3/2 → 4I11/2, and 4F3/2 → 4I13/2 transitions. Er2O3 co-sputtered films presented PL for the 4I11/2 → 4I15/2, and 4I13/2 → 4I15/2 transitions. Tm2O3 co-sputtered films presented PL for the 3H4 → 3H6 transition. Different spectral shapes were observed for the infrared (IR) PL of the Er3+ ions and of the Nd3+ ions for the RE2O3/Si/Al2O3 films with respect to the RE2O3/Si/SiO2 films.

Luminescence of Rare Earth Doped Si/Al/SiO2 Co-Sputtered Films

“…The values in parentheses after the peak values correspond to shoulders and are succeeded by the letters "sh". The thickness of Nd-Si in [11] is 2.2 µm, and the thickness of Nd2P35 in [12] is 4.0 µm so the greater film thickness does not mean greater PL intensity as long as the difference in thickness between the samples is within a certain range, which is the case here. For ease of notation the 4 F 3/2 → 4 I 9/2 emission is labeled as I 926 nm , the 4 F 3/2 → 4 I 9/2 emission is labeled as I 1070 nm and the 4 F 3/2 → 4 I 13/2 emission is labeled as I 1323 nm .…”

“…Nd 3+ : 4 F 3/2 emission spectra had been presented in [11,12] with smaller Nd 2 O 3 target areas. As was mentioned in [11,12] [12]. The thickness of Nd-Si in [11] is 2.2 µm, and the thickness of Nd2P35 in [12] is 4.0 µm so the greater film thickness does not mean greater PL intensity as long as the difference in thickness between the samples is within a certain range, which is the case here.…”

“…Er1P30). The peak position for sample Er1P45 in [12] is 1531 nm and the bandwidth is 15 nm. Positions of the smaller targets with respect to the films are given in the table.…”

“…Each position of a film constitutes a sample (e.g. [12] indicates that for Er doped Si/SiO 2 films the solubility of Er is relatively high. Details of the sputtering conditions and values of the annealing temperature and thickness of the as-deposited samples are shown in Table 1.…”