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Photoluminescence (PL) spectra and PL excitation spectra were recorded at room temperature from SiO2 films implanted with Ge+ ions and annealed at temperature Ta = 450–1100°C under hydrostatic pressure P = 12 kbar. The emergence of features in the violet and green bands of the PL and PL excitation spectra correlates with the formation of hydrostatically strained Ge nanocrystals. The shift of the PL bands to higher energies, which occurs as the annealing temperature is raised to Ta ≥ 800°C, can be attributed to a shift of the energy levels related to the radiative recombination centers, which is caused by the increasing deformation potential. The observed PL is accounted for by the enhanced probability of direct radiative transitions in Ge nanocrystals with an X-like conduction band. © 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

The influence of hydrostatic pressure on photoluminescence of SiO[sub x]N[sub y] (x = 0.25 and y = 1) films grown on the Si substrates and implanted with Ge[sub +] ions, with pressure applied during annealing of the films, was studied for the first time. It is shown that hydrostatic compression leads to a tenfold increase in the photoluminescence intensity of the implanted SiO[sub x]N[sub y] films compared to that obtained as a result of postimplantation annealings at atmospheric pressure. The observed increase in the photoluminescence intensity is attributed to accelerated formation of radiative-recombination centers in the metastable-phase zones in the implanted silicon oxynitride. These centers are tentatively related to ≡Si-Si≡ centers and to complexes involving Ge atoms (of ≡Si-Ge≡ and ≡Ge-Ge≡ types). [ABSTRACT FROM AUTHOR]

Photoluminescence (PL), Raman scattering, and the Rutherford backscattering of α-particles were used to study the formation of the centers of radiative-recombination emission in the visible region of the spectrum on annealing of the SiO[sub 2] layers implanted with Ge ions. It was found that the Ge-containing centers were formed in the as-implanted layers, whereas the stages of increase and decrease in the intensities of PL bands were observed following an increase in the annealing temperature to 800°C. The diffusion-related redistribution of Ge atoms was observed only when the annealing temperatures were as high as 1000°C and was accompanied by formation of Ge nanocrystals. However, this did not give rise to intense PL as distinct from the case of Si-enriched SiO[sub 2] layers subjected to the same treatment. It is assumed that, prior to the onset of Ge diffusion, the formation of PL centers occurs via completion of direct bonds between the neighboring excess atoms, which gives rise to the dominant violet PL band (similar to the PL of O vacancies in SiO[sub 2]) and a low-intensity long-wavelength emission from various Ge-containing complexes. The subsequent formation of centers of PL with λ[sub m] ∼ 570 nm as a result of anneals at temperatures below 800°C is explained by agglomeration of bonded Ge atoms with formation of compact nanocrystalline precipitates. The absence of intense PL following the high-temperature anneals is believed to be caused by irregularities in the interfaces between the formed Ge nanocrystals and the SiO[sub 2] matrix. [ABSTRACT FROM AUTHOR]

The room-temperature photoluminescence emission and excitation spectra of Si[sub 3]N[sub 4] films implanted with Ge[sup +] and Ar[sup +] ions were investigated as a function of the ion dose and temperature of subsequent annealing. It was established that the implantation of bond-forming Ge atoms during annealing right up to temperature T[sub a] = 1000 °C stimulates the formation of centers emitting in the green and violet regions of the spectrum. Implantation of inert Ar[sup +] ions introduces predominantly nonradiative defect centers. Comparative analysis of the photoluminescence spectra, Rutherford backscattering data, and Raman scattering spectra shows that the radiative recombination is due not to quantum-well effects in Ge nanocrystals but rather recombination at the defects ≡Si-Si≡, ≡Si-Ge≡, and ≡Ge-Ge≡. [ABSTRACT FROM AUTHOR]