Table 1 Film parameters as measured by ellipsometry, TEM and XPS.

From: Substoichiometric Silicon Nitride – An Anode Material for Li-ion Batteries Promising High Stability and High Capacity

Film index

Thickness [nm]

Refractive index

Composition, x = [N]/[Si]

Mass density, ρ [g/cm3]

 

Measured, ellipsometry

Measured, TEM

Ellipsometry n (λ = 630 nm)

Ellipsometrya

Ellipsometry,corr.b

XPS

XPS, avg.

ρ l c

ρ p d

A1

42.3 ± 0.8

 

4.28

−0.02

0.01

0.02

0.02 ± 0.00*

2.21

2.17

A2

124.1 ± 0.9

 

4.33

−0.04

−0.01

0.02

   

B1

55.9 ± 0.1

 

3.31

0.35

0.34

0.38

0.39 ± 0.01

2.41

2.15

B2

176.6 ± 0.5

180

3.24

0.38

0.37

0.40

   

C1

46.5 ± 0.1

 

2.78

0.64

0.60

0.59

0.61 ± 0.02

2.52

2.25

C2

127.5 ± 0.3

130

2.82

0.62

0.58

0.63

   

D1

40.0 ± 0.1

 

2.47

0.87

0.79

0.79

0.79 ± 0.01

2.62

2.31

D2

133.6 ± 1.1

135

2.45

0.89

0.80

0.78

   

E1

40.9 ± 0.4

 

2.24

1.08

0.96

0.91

0.89 ± 0.02

2.68

2.44

E2

114.2 ± 0.1

115

2.37

0.96

0.86

0.87

   
  1. aCalculated using equation 1 with n Si  = 4.21 and \({n}_{S{i}_{3}{N}_{4}}=2.01\).
  2. bCalculated using equation 1 with n Si  = 4.30 and \({n}_{S{i}_{3}{N}_{4}}=1.84\).
  3. cCalculated using equation 6 with the average compositions determined from XPS.
  4. dCalculated using the plasmon energy measured using STEM-EELS and equations 2 to 5.
  5. *Given that film A1 and A2 were deposited without ammonia, the small fraction of nitrogen measured in XPS is attributed to experimental error, and these film are regarded as pure silicon.
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