The relaxation of stress-induced dichroism of the 9000nm O infra-red absorption band was investigated in samples of Czochralski material which had been annealed in a H plasma at temperatures of between 225 and 350C. It was found that the in-diffusion of H atoms enhanced the rate of O diffusion (table 185), so that dichroism disappeared gradually from the external surfaces. Other measurements indicated that O diffusion jumps were catalysed by collisions with diffusing H atoms. Increased rates of thermal donor formation were attributed to enhanced long-range O diffusion. It was concluded that H atom concentrations which were as low as 108/cm3 could significantly enhance O diffusivity.

R.C.Newman, J.H.Tucker, A.R.Brown, S.A.McQuaid: Journal of Applied Physics, 1991, 70[6], 3061-70

 

Table 185

Diffusivity of O in Si

 

H-Treatment

T (C)

D (cm2/s)

furnace

385

6.1 x 10-21

furnace

345

3.5 x 10-22

furnace

325

1.2 x 10-22

furnace

325

8.4 x 10-23

plasma

350

2.0 x 10-20

plasma

350

1.2 x 10-20

plasma

325

3.6 x 10-21

plasma

325

2.9 x 10-21

plasma

300

3.0 x 10-21

plasma

300

2.4 x 10-21

plasma

275

3.7 x 10-22

plasma

275

2.4 x 10-22

plasma

250

1.4 x 10-22

plasma

250

1.2 x 10-22

plasma

240

6.3 x 10-23

plasma

240

4.8 x 10-23

plasma

225

1.8 x 10-23

plasma

225

1.1 x 10-23