The luminescence quenching of Er in crystalline Si at temperatures between 77 and 300 K is investigated. Samples were prepared by solid-phase epitaxy of Er-implanted amorphous Si layers with or without O codoping. After epitaxial regrowth at 620 °C, thermal annealing at 900 °C for 30 sec was performed in order to eliminate residual defects in the regrown layer and electrically and optically activate the Er ions. Measurements of photoluminescence intensity and time decay were performed as a function of temperature and pump power. By increasing the temperature from 77 K to room temperature the luminescence intensity decreases by ∼ three orders of magnitude in the Er-doped sample without O codoping, but only by a factor of 30 in the O-doped sample. In this sample room-temperature photo-luminescence and electroluminescence have been observed. Time-decay curves show a fast initial decay (∼100 μsec) followed by a slow decay (∼1 msec), with the relative intensity of these two components depending on temperature, pump power, and O codoping. The decay curves can be fitted by a sum of two exponential functions revealing the existence, in both samples, of two different classes of optically active Er sites. The concentration of excitable sites belonging to the slow-decaying class is similar for the samples with or without O codoping and rapidly decreases when temperature is increased. At temperatures above 150 K the Er luminescence is dominated by the fast-decaying centers the concentration of which is greatly increased by the presence of O. It is found that in the absence of oxygen room-temperature luminescence is hampered by the limited amount of excitable Er ions. In contrast, in O-doped samples the nonradiative decay of excited Er is the main quenching mechanism. The main factors determining the temperature quenching of Er luminescence and the crucial role of oxygen are discussed.

The optical activation, excitation, and concentration limits of erbium in crystal Si are studied. Preamorphized surface layers of Czochralski‐grown (Cz) Si(100), containing 1.7×10¹⁸ O/cm³, were implanted with 250 keV Er at fluences in the range 8×10¹¹–8×10¹⁴ cm⁻². After thermal solid‐phase epitaxy of the Er‐doped amorphous layers at 600 °C, Er is trapped in the crystal at concentrations ranging from 3×10¹⁶ to 7×10¹⁹ Er/cm³, as measured by secondary‐ion‐mass spectrometry. Photoluminescence spectra taken at 77 K show the characteristic Er³⁺ intra‐4f luminescence at 1.54 μm. Photoluminescence excitation spectroscopy shows that Er is excited through a photocarrier‐mediated process. Rapid thermal annealing at 1000 °C for 15 s increases the luminescence intensity, mainly due to an increase in minority‐carrier lifetime, which enhances the excitation efficiency. Luminescent Er forms clusters with oxygen: the maximum Er concentration that can be optically activated is determined by the O content, and is (3±1)×10¹⁷ Er/cm³ in Cz‐Si. The internal quantum efficiency for electrical excitation of Er in Cz‐Si is larger than 3×10⁻⁶.

Plasmonic and dielectric Mie resonances in subwavelength nanostructures provide an efficient way to manipulate light below the diffraction limit that has fostered the growth of plasmonics and nanophotonics. Plasmonic resonances have been mainly related with the excitation of free charge carriers, initially in metals, and dielectric Mie resonances have been identified in Si nanostructures. Remarkably, although much less studied, semi-metals, semiconductors and topological insulators of the p-block enable plasmonic resonances without free charge carriers and dielectric Mie resonances with enhanced properties compared with Si. In this review, we explain how interband transitions in these materials show a major role in this duality. We evaluate the plasmonic and Mie performance of nanostructures made of relevant p-block elements and compounds, especially Bi, and discuss their promising potential for applications ranging from switchable plasmonics and nanophotonics to energy conversion, especially photocatalysis.

Nanocomposite films comprising metal Cu nanocrystals embedded in an Al2O3 matrix were deposited by alternating pulsed laser ablation from metallic Cu and ceramic Al2O3 targets. The films were grown in vacuum on glass substrates held at room temperature. The as-grown films contain 4 nm Cu nanocrystals in an amorphous Al2O3 matrix, with a total thickness of 190 nm. The films show a substantial third-order susceptibility with an electronic nonlinear refractive index of (2.93±1.08)⋅10−10 cm2 W−1 and a nonlinear saturation of −(2.34±0.18)⋅10−5 cm W−1.