Temperature-dependent ion mixing and diffusion during sputtering of thin films of CrSi_2 on silicon

Measurements of sputtering yields and composition profiles have been carried out using backscattering spectrometry for samples of CrSi_2 on Si irradiated with 200‐keV Xe ions. When the CrSi_2 layer is thinner than the ion range, the sputtering yield ratio of Si to Cr increases from 3.5 for room‐temperature irradiation to 65 at 290 °C. For a thick sample, the corresponding increase is from 2.4 to 4.0. only. These changes are explained in terms of a rise in the Si surface concentration at 290 °C. The driving force for this process seems to be the establishment of stoichiometric CrSi_2 compound. Transport of Si to the surface is by ion mixing in the thin sample and thermal diffusion through the thick layer

Chromium silicide formation by ion mixing

The formation of CrSi_2 by ion mixing was studied as a function of temperature, silicide thickness and irradiated interface. Samples were prepared by annealing evaporated couples of Cr on Si and Si on Cr at 450°C for short times to form Si/CrSi_2/Cr sandwiches. Xenon beams with energies up to 300 keV and fluences up to 8 X 10^15 cm^(-2) were used for mixing at temperatures between 20 and 300°C. Penetrating only the Cr/CrSi_2 interface at temperatures above 150°C induces further growth of the silicide as a uniform stoichiometric layer. The growth rate does not depend on the thickness of the initially formed silicide at least up to a thickness of 150 nm. The amount of growth depends linearly on the density of energy deposited at the interface. The growth is temperature dependent with an apparent activation energy of 0.2 eV. Irradiating only through the Si/CrSi_2 interface does not induce silicide growth. We conclude that the formation of CrSi_2 by ion beam mixing is an interface-limited process and that the limiting reaction occurs at the Cr/CrSi_2 interface

Influence of F and Cl on the recrystallization of ion-implanted amorphous Si

The effect of fluorine and chlorine implantation on the solid-phase epitaxial regrowth of amorphized Si was studied in intrinsic and heavily boron doped material. Annealings were performed at 500 and 600°C. Both F and Cl retard the regrowth rate at 500°C. The growth rates are much faster in B-doped than in undoped Si. Complete regrowth in B-doped Si is obtained for all investigated doses of fluorine up to 5×10^15 F/cm^2 at 600°C for 30 min. The highest dose of chlorine (5×10^15 Cl/cm^2) stops the regrowth at this temperature

An inert marker study for palladium silicide formation: Si moves in polycrystalline Pd2Si

A novel use of Ti marker is introduced to investigate the moving species during Pd2Si formation on and Si substrates. Silicide formed from amorphous Si is also studied using a W marker. Although these markers are observed to alter the silicide formation in the initial stage, the moving species can be identified once a normal growth rate is resumed. It is found that Si is the dominant moving species for all three types of Si crystallinity. However, Pd will participate in mass transport when Si motion becomes obstructed

Phase-locked semiconductor laser array with separate contacts

A new monolithic phase-locked semiconductor laser array has been fabricated. Employing two-level metallization, each of the eight elements in the array has a separate contact, thus making it possible to compensate for device nonuniformities and control the near-field and far-field patterns. Threshold currents are approximately 60 mA for each 5-µm-wide laser in the array. Phase locking has been observed via the narrowing of the far-field pattern. Experimental results are compared to those obtained from the same arrays operated with all the lasers connected in parallel