The radiation-enhanced diffusion of implanted Au markers in amorphous Si was measured at 77 to 693K (table 11). The samples were bombarded with 2.5MeV Ar ions, and the diffusion coefficients exhibited 3 well-defined ranges. Below 400K, the diffusion was athermal and was due to ballistic mixing. At temperatures ranging from 400 to 700K, the diffusion was of Arrhenius type; with an activation energy of 0.37eV. It was considerably enhanced with respect to normal thermal diffusion. The defects which caused the enhanced diffusion arose from nuclear energy loss processes. Thermal diffusion, with an activation energy of 1.42eV, predominated at temperatures greater than 750K.

Radiation-Enhanced Diffusion of Au in Amorphous Si. F.Priolo, J.M.Poate, D.C.Jacobson, J.Linnros, J.L.Batstone, S.U.Campisano: Applied Physics Letters, 1998, 52[15], 1213-5

 

Table 11

Radiation-Enhanced Diffusivity of Au in Amorphous Si

 

Dose (Au/cm2)

Temperature (C)

D (cm2/s)

2 x 1015

407

1.4 x 10-14

2 x 1015

367

7.2 x 10-15

2 x 1015

312

3.4 x 10-15

2 x 1015

242

1.4 x 10-15

2 x 1015

157

3.4 x 10-16

5 x 1014

407

1.3 x 10-14

5 x 1014

367

6.4 x 10-15

5 x 1014

312

3.8 x 10-15

5 x 1014

242

1.6 x 10-15

 

Table 12

Diffusion of Au in Amorphous Si Multi-Layers

 

Repeat Length (nm)

T (C)

Diffusion Length (nm)

D (cm2/s)

4.8

200

0.23

6.0 x 10-20

4.8

200

0.32

2.5 x 10-20

4.7

220

0.34

3.9 x 10-19

4.7

220

0.44

6.3 x 10-20

4.7

220

0.46

3.0 x 10-21

4.7

240

0.39

1.7 x 10-18

4.7

240

0.52

1.8 x 10-19

4.5

250

0.37

2.3 x 10-18

4.5

250

0.42

4.5 x 10-19

4.4

260

0.35

4.0 x 10-18

4.4

260

0.39

2.8 x 10-19

4.4

260

0.50

4.6 x 10-20

4.6

260

0.31

3.2 x 10-18

4.6

260

0.43

5.9 x 10-19

4.6

260

0.49

5.7 x 10-20

4.6

260

0.51

1.7 x 10-20