Chapter 6 Studies on Pure and Co Doped MgTiO 3
6.3 MgTiO 3 thin films
6.3.2 Structure and microstructure of MTO thin films
All the as - deposited films were found to be amorphous and become crystalline after the post - deposition annealing at 700oC for 1 h irrespective of substrates used. It is well known that the oxide films grow naturally in an amorphous form unless the required activation is provided either in the form of the temperature or the ion bombardment to initiate the crystal growth. Upon annealing at 700oC for 1 h, the MTO thin films exhibited evidence of conversion from an amorphous state to polycrystalline trigonal phase. The XRD patterns of the MTO films deposited onto quartz and amorphous SiO2 under different OMP are shown in Figure 6.2. Along with trigonal phase a secondary phase MgTi2O5 is observed for the films deposited on amorphous SiO2 substrates. These results indicate that the intensities of the (104), (113) and (116) peaks were decreasing gradually with increasing OMP for MTO films on both the substrates. The average crystallite size of the annealed films was estimated using Scherrer’s equation [14].
θ β
λ cos D K
esize
Crystallit = (6.1)
where K - Scherrer constant, where λ is wavelength of X - ray (=1.5406 Å) , β is full width and half maxima, θ is Bragg’s angle. Figure 6.3 shows the variation in crystallite size as a function of OMP for the films deposited on quartz, amorphous SiO2 and platinized silicon substrates. One can observe that a decrease in the average crystallite size with an increase in OMP from 33 to 19 nm, 29 to 21 nm and 27 to 21 nm for quartz, amorphous SiO2 and platinised silicon substrates, respectively. This indicates that films deposited at higher OMP
were less crystallined. This may be due to the decrease in rate of deposition, which causes lowering of thickness of thin
Figure 6.2: XRD patterns of MTO thin films percentage and annealed at 700
were less crystallined. This may be due to the decrease in rate of deposition, which causes thin films.
XRD patterns of MTO thin films deposited under different oxygen mixing percentage and annealed at 700oC for 1h on (a) quartz (b) amorphous SiO
were less crystallined. This may be due to the decrease in rate of deposition, which causes
deposited under different oxygen mixing on (a) quartz (b) amorphous SiO2 and (c)
Figure 6.3: The variation in average crystallite size as a function of oxygen mixing percentage.
In order to confirm the chemical composition of the deposited MTO thin films, energy dispersive spectroscopy (EDS) analysis was performed on the films deposited on quartz substrates.
Figure 6.4: (a) SEM image and (b) EDS spectrum of the MTO thin film at 70% OMP and annealed at 700
Figure 6.4(a) and 6.4(b) shows the microstructure and EDS spectrum of annealed MTO thin film deposited at 70% OMP, respectively and the elemental percentages are summarized in Table 6.1. It is found that the composition of the target is nearly achieved in the deposited thin films. The rate of deposition of Mg atoms is slightly higher than Ti atoms because Ti atomic weight is higher than Mg atoms. The
The variation in average crystallite size as a function of oxygen mixing
der to confirm the chemical composition of the deposited MTO thin films, energy dispersive spectroscopy (EDS) analysis was performed on the films deposited on quartz
(a) SEM image and (b) EDS spectrum of the MTO thin film deposited on quartz at 70% OMP and annealed at 700oC for 1 h.
Figure 6.4(a) and 6.4(b) shows the microstructure and EDS spectrum of annealed MTO thin film deposited at 70% OMP, respectively and the elemental percentages are summarized ound that the composition of the target is nearly achieved in the deposited thin films. The rate of deposition of Mg atoms is slightly higher than Ti atoms because Ti atomic weight is higher than Mg atoms. The slight deficiency of the oxygen can be due to
The variation in average crystallite size as a function of oxygen mixing
der to confirm the chemical composition of the deposited MTO thin films, energy dispersive spectroscopy (EDS) analysis was performed on the films deposited on quartz
deposited on quartz
Figure 6.4(a) and 6.4(b) shows the microstructure and EDS spectrum of annealed MTO thin film deposited at 70% OMP, respectively and the elemental percentages are summarized ound that the composition of the target is nearly achieved in the deposited thin films. The rate of deposition of Mg atoms is slightly higher than Ti atoms because Ti deficiency of the oxygen can be due to
multicomponent materials can be easily grown in the stoichiometric state by using RF sputtering technique.
Table 6.1: The required and obtained percentages of Element Weight (%)
O K 39.13
Mg K 21.72
Ti K 39.15
Total 100.00
The AFM images of as
substrates were shown in Figure 6.5(a) and 6.5(b), respectively. It is evident that the as deposited film does not show any apparent grain structure. On the other hand, the annealed films reveal the homogeneous nano
about 35 - 40 nm. Post deposition annealing enhanced the roughness and improved the grain growth which improves the packing density of the films.
deposition of the films are 2.6
deposition and the thickness of the thin films were decreased. The thickness of the thin films was in the range of 460 - 350 nm and 380
respectively.
Figure 6.5: Atomic force microscopic (AFM) images of (a) as
multicomponent materials can be easily grown in the stoichiometric state by using RF
: The required and obtained percentages of elements in MTO films
Weight (%) Atomic (%) Required Obtained
39.13 58.84 3
21.72 21.50 1
39.15 19.66 1
100.00
The AFM images of as - deposited and annealed MTO films deposited on quartz shown in Figure 6.5(a) and 6.5(b), respectively. It is evident that the as deposited film does not show any apparent grain structure. On the other hand, the annealed films reveal the homogeneous nano - sized grain morphology with an average grain size of 40 nm. Post deposition annealing enhanced the roughness and improved the grain growth which improves the packing density of the films. The magnitudes of rate of deposition of the films are 2.6 - 2 nm per minute. With an increase in the OMP, the
deposition and the thickness of the thin films were decreased. The thickness of the thin films 350 nm and 380 - 305 nm for the as - deposited and annealed films,
Atomic force microscopic (AFM) images of (a) as - deposited and (b)
multicomponent materials can be easily grown in the stoichiometric state by using RF
Obtained 2.94 1.08 0.98
deposited and annealed MTO films deposited on quartz shown in Figure 6.5(a) and 6.5(b), respectively. It is evident that the as - deposited film does not show any apparent grain structure. On the other hand, the annealed
sized grain morphology with an average grain size of 40 nm. Post deposition annealing enhanced the roughness and improved the grain The magnitudes of rate of 2 nm per minute. With an increase in the OMP, the rate of deposition and the thickness of the thin films were decreased. The thickness of the thin films deposited and annealed films,
deposited and (b) annealed