Segregation and diffusion of phosphorus from doped Si1−xGex films into silicon (original) (raw)
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Phosphorus Diffusion From Doped Si1−xGex, Films into Silicon
MRS Proceedings, 1999
ABSTRACTPhosphorus diffusion from in-situ doped Si1−xGex epitaxial films into Si at 800°C was investigated using secondary ion mass spectroscopy and differential resistance measurements. The surface P concentration in the diffused layer in Si was higher than the P concentration in the Si1−xGex, film in the present conditions, which signifies the segregation of P from the Si1−xGex, film into Si. The segregation coefficient, defined as the ratio of the active P concentration in the Si to that in the Si1−xGex, film, was about 2.5 in the case of the Si0.75Ge0.25 film as a diffusion source and increased with increasing Ge fraction. The P diffusion profiles in Si were normalized by x/√, even though the segregation of P occurred. The high concentration diffusion characteristics of P in Si were similar to those reported by using conventional diffusion sources.
Activation volume for phosphorus diffusion in silicon and Si[sub 0.93]Ge[sub 0.07]
Applied Physics Letters, 2005
The hydrostatic pressure dependence of the diffusivity of P in compressively strained Si 0.93 Ge 0.07 and unalloyed Si has been measured. In both cases the diffusivity is almost independent of pressure, characterized by an activation volume V * of ͑+0.09± 0.11͒ times the atomic volume ⍀ for the unalloyed Si, and ͑+0.01± 0.06͒ ⍀ for Si 0.93 Ge 0.07 . The results are used in conjunction with the reported effect of biaxial strain on diffusion normal to the surface to test the prediction for an interstitialcy-based mechanism of Aziz's phenomenological thermodynamic treatment of diffusion under uniform nonhydrostatic stress states. The prediction agrees well with measured behavior, lending additional credence to the interstitial-based mechanism and supporting the nonhydrostatic thermodynamic treatment.
Applied Physics Research, 2015
In this work, we try to make a p-type monocristalline silicon pn junction using an easier doping method. We combined spin-coating thin film deposition method and solid doping technique. This technique can be considered as variety of the SOD method. In this study, phosphorous-based gel compounds was prepared and deposited by spin coating. Heat treatment would thus, after deposition of thin layer, diffuse phosphorus atoms into the substrate to obtain a pn diode. Study by Secondary Ions Mass Spectrometry (SIMS) showed a surface phosphorus concentration of 10 20 at/cm 3 incorporated within the silicon substrate to a depth of 300 nm. The microwave phase-shift (µW-PS) technique is used to determine the bulk lifetime (τ b) of minority carriers. In this technique, the phase-shift between a microwave beam (10 GHz) and a sine-modulated infrared excitation is related to τ b and to the surface recombination velocity (S) (Palais, Clerc, Arcari, Stemmer & Martinuzzi, 2003). The lifetime τ b mean values vary from 7 µs for a p-type Silicon to 97 µs for phosphorus-diffused silicon. The surface recombination velocity S varies from around 500 to 1000 cm.s-1 .
In order to increase the conversion efficiencies of silicon solar cells, advanced cell structures with selectively doped areas receive an increasing interest. There is a strong need to separate the contacted diffusion profiles from the non-contacted. On the one hand, a high dopant concentration in the contact regime reduces the series resistance losses mainly due to lowered contact resistance. Additionally recombination is reduced by shielding the minority charge carriers from surface at the contact. On the other hand a low dopant concentration in the non-contact regime reduces the recombination losses and optimizes the spectral response of the cell.
The simple approach to determination of active diffused phosphorus density in silicon
The diffusion of Phosphorus in silicon using a POCl 3 source has been considered. In the base of Fair-Tsai model of P-diffusion an empirical equation for calculation of active diffused phosphorus density (Q el ), is proposed. In this equation, a relationship between (Q el ), diffusion time, temperature and junction depth of P-diffused layer (X j ), is presented. The value of sheet resistance (R s ), which is taken from theoretical determination at 900°C, has a good agreement with experimental result.
ToF-SIMS study of phosphorus diffusion in low-dimensional silicon structures
Surface and Interface Analysis, 2013
Doping of Si nanocrystals is expected to be crucial in order to tailor the properties of these nanostructures and to implement their technological applications. In this work, phosphosilicate ultra-thin films (P d-layers) were buried in an SiO/SiO 2 multilayer structure, and the redistribution of P atoms during high-temperature (800-1100 C) thermal treatments was studied by means of ToF-SIMS depth profiling. We demonstrated that the presence of the surrounding SiO 2 matrix provides a strong barrier to P diffusion and, for temperatures equal or above 1000 C, induces P segregation in the SiO regions, where two-dimensional layers of Si nanocrystals are formed during the thermal treatment. Such an effect is qualitatively in agreement with the P diffusivity data reported in the literature. The amount of P atoms incorporated in the Si nanocrystal region is directly controlled through a limited source process by properly adjusting the thickness of the P d-layer interposed between the SiO and SiO 2 films.
Journal of The Electrochemical Society, 1994
As device dimensions shrink to submicron levels, good design of ultrashallow junctions has become increasingly important. It is in this context that the use of carbon/oxygen as a possible diffusion-suppressing agent for phosphorus has been suggested. To study this complex phenomenon, this experimental study looks at the effects of low dose silicon, carbon, and oxygen implantation damage on the diffusion of lightly doped phosphorus layers. The effects of a silicon and carbon coimplant on the diffusion of phosphorus are studied as part of a second experiment. Finally, lightly doped drain structure is annealed in the presence of a carbon implant. Carbon is the most effective diffusion-suppressing agent among the three species. Results from the second experiment suggest that carbon strongly affects the interstitial profile, and thereby the final phosphorus profile.
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1989
was implanted at doses below amorphization threshold in virgin silicon and in silicon containing interstitial dislocation loops. The loops were formed by high dose Si+ Implantation and 9CJO" C, 30 min annealing. Triple-crystal X-ray diffraction and secondary ion mass spectrometry were used for the analysis of implant defects and the determination of P distribution, respectively. Anneal@ were carried out in a furnace in the range between 600 and 900 o C, and by an electron beam at 1000 o C for 10 s. The results obtained show that the presence of loops strongly reduces the phosphorus anomalous diffusion. This phenomenon is a consequence of the absorption by the loops of the interstitial excess coming from dissolution of the clusters produced by the P implant. The influence of the loop position with respect to the P distribution on the extent of P diffusivity is analyzed and discussed.