An integrated study of diffusion, solubility, and electrical properties of scandium and praseodymium in silicon annealed in various media and temperature ranges (1100-1280°С) was performed for the first time. The tracer technique, autoradiography, measurements of isothermic capacity and current relaxation, conductivity, and the Hall effect were used for the investigations. The diffusion parameters, solubility, and an acceptor character of scandium and praseodymium impurities in silicon were determined.Recently silicon doped with rare earth elements (REE) has attracted increasing attention of researchers as a candidate material for optoelectronics. This is due both to the fact that the Si structures hold much promise in silicon optoelectronics as light sources (for example, for Si, the wavelength 1.54 µm means the minimal loss and dispersion in the optical-fiber communication lines) and to the special features of electron shells of the elements of this group [1,2]. The efficiency of rare earth impurities in silicon and manifestation of optical properties of the structures depend on the spectrum of electrically and optically active centers containing REEs, as well as on the total concentration and REE diffusion mechanism.The aim of the work was an integrated study of diffusion, solubility, and electrical properties of scandium and praseodymium in silicon.A metal layer of the radioactive isotope 46 Sc was deposited, or a scandium chloride layer labelled by the radioactive isotope 46 Sc and a praseodymium chloride layer containing an oxide of the radioactive isotope 143 Pr 2 O 3 were put from solution onto the surfaces of silicon samples of the n-type with the specific resistance ρ = 15-100 Ω·cm. The area and thickness of the samples were ∼1.5-2.5 cm 2 and ∼350-380 µm, respectively.To study electrical properties, the stable isotopes of scandium and praseodymium metals or three-valence salts of scandium and praseodymium chlorides were used as diffusates. Diffusion annealing was performed at 1100-1280°С in the vacuum ampoules (~10 -5 -10 -7 mmHg) in the air or in the evacuated ampoules in the argon atmosphere. The diffusion annealing time was varied in the interval from 5 to 72 hours depending on the diffusion temperatures.After diffusion annealing, the samples were rinsed many times in the hydrofluoric acid, chloroazotic acid, and boiling H 2 O 2 :HCl solution. Then, a layer (~ 100 µm) much thicker than the diffusion depth (~10 µm) was removed from the sample edges.The profiles of diffusates were determined by the sectioning method -etching of thin layers (in the solution HF:HNO 3 = 1:50 followed by washing in the H 2 O 2 :HCl mixture) and measuring the residual activity of the samples using a low background noise UMF-1500М facility with a β-counter SBT-11. The 46 Sc and 143 Pr spectra were identified by measurements performed using a pulse analyzer AI-1024 (A. F. Ioffe Physical Technical Institute of the Russian Academy of Sciences, St. Petersburg). The thickness of etched layers (0.05-0.5 µm) was determined...
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