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By means of Rutherford backscattering spectrometry, electron microscopy, and energy-dispersive X-ray spectroscopy, the distribution and interaction of In and As atoms implanted into thermally grown SiO2 films to concentrations of about 1.5 at % are studied in relation to the temperature of subsequent annealing in nitrogen vapors in the range of T = 800–1100°C. It is found that annealing at T = 800–900°C results in the segregation of As atoms at a depth corresponding to the As+-ion range and in the formation of As nanoclusters that serve as sinks for In atoms. An increase in the annealing temperature to 1100°C yields the segregation of In atoms at the surface of SiO2 with the simultaneous enhanced diffusion of As atoms. The corresponding diffusion coefficient is DAs = 3.2 × 10–14 cm2 s–1. [ABSTRACT FROM AUTHOR]

The properties of germanium implanted into the SiO2 layers in the vicinity of the bonding interface of silicon-on-insulator structures are studied. It is shown that, under conditions of high-temperature (1100°C) annealing, germanium nanocrystals are not formed, while the implanted Ge atoms segregate at the Si/SiO2 bonding interface. It is established that, in this case, Ge atoms are found at sites that are coherent with the lattice of the top silicon layer. In this situation, the main type of traps is the positive-charge traps; their effect is interpreted in the context of an increase in the surface-state density due to the formation of weaker Ge-O bonds. It is found that the slope of the drain-gate characteristics of the back MIS transistors increases; this increase is attributed to an increased mobility of holes due to the contribution of an intermediate germanium layer formed at the Si/SiO2 interface. [ABSTRACT FROM AUTHOR]

The influence of hydrostatic compression on the implantation-induced synthesis of Ge nanocrystals in SiO[sub 2] host was studied. It is found that high-temperature annealing under pressure leads to retardation of Ge diffusion in SiO[sub 2]. It is shown that unstressed Ge nanocrystals are formed as a result of conventional annealing (under atmospheric pressure). Annealing under pressure is accompanied by formation of hydrostatically stressed Ge nanocrystals. The stress in Ge nanocrystals was determined from optical-phonon frequencies in the Raman spectra. The shift of Raman resonance energy (E[sub l], E[sub 1] + Δ[sub l]) corresponds to the quantization of the ground-state energy for a two-dimensional exciton at the critical point M[sub 1] of germanium. It is ascertained that a photoluminescence band peaked at 520 nm is observed only in the spectra of the films which contain stressed Ge nanocrystals. [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]