On the solubility and diffusion coefficient of tritium in single crystals of silicon

Abstract

The solubility and the diffusion coefficient of tritium in silicon were measured. The samples were of p-typesilicon, with a resistivity of 150Ωcm and with dimensions of 10 × 5 × 2 ∼ 0.5 mm. The samples were put into fused silica ampoules and tritium, under 100 mm Hg and at 20°C, was introduced into them. The ampoules were then heated at 900 ∼ 1200°C for an hour. The samples thus prepared were placed in another ampoule connected to the gas ionization chamber and heated at 1000°C and the total amount of tritium evolved from the silicon was estimated. The solubility was expressed by: S = 1·6 × 10 20 exp (−34000/ RT) atoms cm −3 under 1 atm of tritium. The diffusion coefficient, D, was also estimated from the out-diffusion of tritium at 400 ∼ 500°C: it is given by: D = 4·2 × 10 −5 exp (−13000/ RT) cm 2 sec −1.