Hetero- and homoepitaxial Nd3+-doped LaF3 thin films grown by molecular beam epitaxy: A spectroscopic study

Abstract

Hetero- and homoepitaxial Nd3+-doped LaF3 thin films have been grown by molecular beam epitaxy. Two different orientations of CaF2 substrates, (111) and (110), have been used for the heteroepitaxial structures. High-resolution emission and excitation spectra as well as the decay time of the emission have been measured. The spectroscopic measurements demonstrate that one Nd3+ site is present in the LaF3 layers grown on CaF2(111) substrates but two slightly different Nd3+ centers are resolved in the films on CaF2(110) substrates. One Nd3+ site has been found in the homoepitaxial sample. Slight differences are observed between the centers found in the LaF3 layers and the one observed in the Nd3+-doped LaF3 bulk crystal. For the homoepitaxial layer, the linewidths are similar to those of the bulk crystals, whereas for the heteroepitaxial layers, a broadening is observed.

Low phonon energy, Nd:LaF/sub 3/ channel waveguide lasers fabricated by molecular beam epitaxy

“…The Nd-doping level was chosen to be 1 at.%, corresponding to LaF and NdF cell temperatures of 1165 C and 993 C, respectively. In previous work, we have reported high-resolution excitation spectroscopy, emission spectroscopy, and lifetime measurements on hetero-and homoepitaxial layers in order to determine the influence of the substrate on the crystal quality and the influence of the Nd doping level on spectroscopic properties [18]. It was found that the highest luminescence intensity is obtained in the samples doped with 1 at.% Nd.…”

Atomic-Scale Structural Analysis of Homoepitaxial LaF3:Yb,Tm Core–Shell Upconversion Nanoparticles Synthesized through a Microwave Route

“…This is consistent with other reports in the literature in which homoepitaxial designs in thin films have led to spectroscopic changes such as decreased inhomogeneous broadening in the luminescence. 35 In our case, the observed enhancement with similar factors at all emission wavelengths can be attributed to the reduced surface defects in addition to a possible additional energy transfer from Yb 3+ ions in the shell layer to the luminescent Tm 3+ ions in the core. By comparison, XRD data of the inert shell confirms an altered crystal field around luminescent Tm ions in the core through its effect on enlarged hexagonal lattice parameters and even eliminated tensile strain.…”

Molecular-beam-epitaxy growth and luminescence properties of Nd3+-doped LaF3/CaF2 thin films

“…We have identified, by growing layers with different thicknesses, that the two centers in the films grown on the ͑110͒ substrate are not specifically associated with the layer-substrate interface, but both present throughout the thickness of the film. 6 The luminescence decay curves are mainly nonexponential at a short-time range and exponential at long times for all the samples. Figure 5 gives the results for the decay times of Fig.…”

“…Furthermore, two inequivalent Nd 3ϩ sites can be identified from a careful study of the emission and excitation spectra for the layers grown on the ͑110͒ face of CaF 2 . 6 The arrows in Fig. 4 indicate the positions of the transition 4 F 3/2 (1)→ 4 I 11/2 (1) for the two centers.…”

“…5 We have also reported the spectroscopic results of 1.06 and 1.3 m infrared emissions of Nd 3ϩ in both the heteroepitaxial films on CaF 2 substrates and the homoepitaxial ones on LaF 3 substrates. 6,7 This article presents a brief report of some important results achieved by our group with a special emphasis on the temperature-dependence study of infrared emissions with the temperature ranging from 25 to 300 K. …”