Some DLTS results'

1
Some DLTS results.

• J.H. Bleka et al.
• University of Oslo, Department of Physics,
  Physical Electronics,
• P.O. 1048 Blindern, N-0316 Oslo, NORWAY
• and
• University of Oslo, Centre for Materials Science
  and Nanotechnology P.O. 1128 Blindern,
  N-0318 Oslo, NORWAY

Department of Physics
2
Topics

• - Neutron-irradiated samples first results
• Low temperature defect annealing

3
Samples neutron irradiation
P- n- - n Si diodes, processed by CIS std,
(8556-02) MCz lt100gt, 1 kOcm, 300 µm 1 MeV
neutrons at RT, 3.5x1011 and 6.7x1011 cm-2
(DLTS) Storage at -20 C
4
Results neutron irradiation
0.43 eV
Ec-0.18 eV
E4
0.23 eV
5
Results neutron irradiation
0.43 eV
Ec-0.18 eV
E4
0.23 eV
6
Results neutron irradiation
Local Fermi level pinning??!
7
Defect tracks in Si
3 MeV Au single ion impact
Vacancy distribution
Monakhov et al., Phys. Rev. B65, 245201 (2002)
Vines et al., Phys. Rev. B73, 085312 (2006)
8
Samples LT defect annealing
P- n- - n Si diodes, standard process by
SINTEF MCz, SFz as processed MCz, SFz
pre-annealed at 450 ºC for 1h MCz, SFz
hydrogenated in HF 450 ºC, 1h 6 MeV electrons
at RT, 2-5x1012 cm-2 Storage at -20 C
9
P-n--n MCz diode Nd5x1012 cm-3 6 MeV e-,
5x1012 cm-2
Bleka et al., ECS Trans 3, 387 (2006)
10
VO, V2/-, V2-/0 and E4 vs time at RT
P-n--n MCz diode Nd5x1012 cm-3 6 MeV e-,
5x1012 cm-2
11
Loss of VO, V2/- and V2-/0 vs loss of E4
P-n--n MCz diode Nd5x1012 cm-3 6 MeV e-,
5x1012 cm-2
12
Difference between DLTS spectra
E5
P-n--n MCz diode Nd5x1012 cm-3 6 MeV e-,
5x1012 cm-2
E4 Ec-0.37 eV sapp10-14 cm2 E5 Ec-0.45
eV sapp3x10-15 cm2
13
Further results (I)
E4/E5 occur with the same relative initial
concentration (25 of V2) and exhibit the same
annealing rate at RT irrespective of MCz
(as-processed, pre-annealed, pre-annealedhydrogen
ated), SFz (as-processed, pre-annealed,
pre-annealedhydrogenated) and DOFZ
(as-processed, pre-annealed, pre-annealedhydrogen
ated)
14
Further results (II)

• Isothermal annealing of E4/E5 at 22 C (RT), 40.5
  C, 55 C and 65 C yield
• First order kinetics (exponential decay)
• Activation energy of 1.27 eV
• Prefactor of 2.1x1015 s-1

Cf values for reverse annealing by Moll et
al. Activation energy 1.33 eV Prefactor
1.5x1015 s-1 !!!!!
15
Filling pulse measurements for the VO peak
P-n--n SFz diode Nd4x1012 cm-3 6 MeV e-,
2x1012 cm-2
CsCi (and Ci) is not involved in the annealing of
E4/E5
16
Speculations
V Y ? E4 V Oi ? VO Y E4Oi/VO
2x1016 cm-3 YCs?? Not consistent with the
results for oxygen-lean SFz
17
Speculations
V Y ? E4 V Oi ? VO Y E4Oi/VO
2x1016 cm-3 YCs?? Not consistent with the
results for oxygen-lean SFz
E4 ? VO Y Y Sii ??
Further work remains
18
Acknowledgements

• Financial support from
• - the Norwegian Research Council (NFR Strategic
  programs on micro/nanotechnology and materials
  science (NANO/FUNMAT))
• the Nordic Research Training Academy (NorFA)
• - University of Oslo (Functional materials
  program)
• is gratefully acknowledged.