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Chapter 5
2,0 Mo 15 *
Sheet resistance (/) 1,5
1,0
Mo 2
0,5
*
0,0
0 50 100 150
Figure 5.20 Time at damp heat (hours)
o
Sheet resistance of Mo25/2 and Mo25/15 as a function of exposure time to 85 C/85% RH. Every data point represents five
measurements on different positions of the samples. * Another measurement was executed after 150 hours, but the layers
did not show any conductivity after this duration.
5.3.2.4 Compositional changes
The compositional changes have been studied with SEM-EDX, SIMS and XPS, as
described in this chapter. Furthermore, Raman spectroscopy and XRD were utilised,
which gave results similar to the selenised samples in the ‘selenisation and pressure’
study: Raman spectroscopy showed the presence of MoSe, MoO , Mo O and MoO
4
2
2
3
11
type bonds, while very low signals for carbon and carbon hydrides or carbon nitrides
were likely also present. XRD indicated the presence of a low amount of crystalline
molybdenum oxide species, which can partly be identified by molybdenum suboxides,
with compositions in between MoO and MoO .
3
2
5.3.2.4.1 SEM-EDX
In optical microscopy, changes of morphology on the surface were already detected
after several hours of damp heat treatment. Various SEM pictures (Figure 5.21) show
examples of the morphology on Mo25/2 and Mo25/15. The SEM pictures revealed the
occurrence of among others needles, stains and crystalline bars. EDX measurements
were taken on the surface of non-degraded and degraded samples after various
degradation times in order to globally determine the composition of the different
regions. Table 5.7 shows the EDX analysis before and after damp heat exposure – it
should be noted that the penetration depth is likely similar to the sample thickness, so
perfect analysis of the particle composition is not possible.
Before damp heat exposure, molybdenum and selenium as well as low concentrations
of oxygen and carbon were found in EDX measurements. After exposure, measurements
were executed both on the ‘clean’ area and on areas with different types of needles and
152
2,0 Mo 15 *
Sheet resistance (/) 1,5
1,0
Mo 2
0,5
*
0,0
0 50 100 150
Figure 5.20 Time at damp heat (hours)
o
Sheet resistance of Mo25/2 and Mo25/15 as a function of exposure time to 85 C/85% RH. Every data point represents five
measurements on different positions of the samples. * Another measurement was executed after 150 hours, but the layers
did not show any conductivity after this duration.
5.3.2.4 Compositional changes
The compositional changes have been studied with SEM-EDX, SIMS and XPS, as
described in this chapter. Furthermore, Raman spectroscopy and XRD were utilised,
which gave results similar to the selenised samples in the ‘selenisation and pressure’
study: Raman spectroscopy showed the presence of MoSe, MoO , Mo O and MoO
4
2
2
3
11
type bonds, while very low signals for carbon and carbon hydrides or carbon nitrides
were likely also present. XRD indicated the presence of a low amount of crystalline
molybdenum oxide species, which can partly be identified by molybdenum suboxides,
with compositions in between MoO and MoO .
3
2
5.3.2.4.1 SEM-EDX
In optical microscopy, changes of morphology on the surface were already detected
after several hours of damp heat treatment. Various SEM pictures (Figure 5.21) show
examples of the morphology on Mo25/2 and Mo25/15. The SEM pictures revealed the
occurrence of among others needles, stains and crystalline bars. EDX measurements
were taken on the surface of non-degraded and degraded samples after various
degradation times in order to globally determine the composition of the different
regions. Table 5.7 shows the EDX analysis before and after damp heat exposure – it
should be noted that the penetration depth is likely similar to the sample thickness, so
perfect analysis of the particle composition is not possible.
Before damp heat exposure, molybdenum and selenium as well as low concentrations
of oxygen and carbon were found in EDX measurements. After exposure, measurements
were executed both on the ‘clean’ area and on areas with different types of needles and
152
