Natali et al. - Structural Characterization of Lead Zirconate Titanate thin films prepared on different electrods and on silicon substrates - Supplementary Material
1. High resolution XRD 2

-

scans
Besides GIXRD spectra we also recorded 2

-

scans in Bragg - Brentano geometry (2

step size.
0.03 deg) for both the substrate and the films to evaluate preferential orientations and crystallite sizes as well as to help in phase identification. A typical set of 2

-

scans is shown in Figure 1. a) b) c) d)
20 25 30 35 40 45 50 55 60
2 theta (deg)
Fig. 1 2

-

XRD scans for ITO/glass substrate (curve a) and PZT films on ITO: "as-grown" (curve b), annealed 650 o C
(curve c) and annealed 750 o C (curve d). The intensity scale has been multiplied by x 4 for curves a) and b) to evidence more celarly weak peaks. Identified phases: open squares: rhombohedral perovskite PZT (JCPDS-ICCD 01-073-2022), full square: scrutinyite

PbO
2
(01-72-2102, full circle: PbO
1,37
(00-027-1202).
2. Identification of phases
Identification of the lead oxide phases and pyrochlore PZT phases in the "as grown" could not be easily done from the 2

-

scans due to weak intensity of the lead-oxide peaks. Identification of these phases was done on GIXRD spectra that greatly enhance the film/subtrate signal ratio. On the other hand identification of the perovskite phase was easier from the 2

-

scans due to reduced instrumental peak broadening in the Bragg-Brentano geometry compared to the GIXRD geometry.
In the following we report the list of lattice-spacing differences for identified phases and indexed peaks
 d(hkl)=d(hkl)exp-d(hkl)JCPDS. Where not otherwise specified lattice spacings were

determined from 2

-

scans.
JCPDS-ICCD reference patterns of identified phases are: PbO
1,37
(00-
027-1202), litharge PbO (01-085-1739), scrutinyite

PbO
2
(01-72-2102), rhombohedral PZT perovskite (01-073-2022). For the pyrochore phase the only pattern found in the database was
JCPDS-ICDD 00-026-0142 corresponding to Pb
2
Ti
2
O
6.
Since the actual composition of the pyrochlore phase determined by RBS in our samples is Pb
2.5
(Zr
0.51
Ti
0.49
)
2
O
6.2
we do not attempt to estimate
 d(hkl) values in this case.
"as grown" samples: (GIXRD spectra) 1) PZT on silicon: PbO:
 d(110)=-0.039
Å , PbO
1,37
:
 d(113)=0.036
Å ,
 d(221)=0.0054
Å ,
 d(501)=0.0074
Å ,
 d(006)=-0.0018
Å , PbO
2
:
 d(110)=0.0127
Å ,
 d(002)=-0.0048
Å. 2) PZT on Pt: PbO
1,37
:
 d(113)=0.048
Å ,
 d(501)=0.0048
Å , PbO
2
:
 d(110)=-0.02
Å ,
 d(220)=-0.0047
Å. 3) PZT on ITO: PbO
2
:
 d(110)=-
0.04
Å ,
 d(220)=-0,01 Å. 4) PZT on Au: PbO
1,37
:
 d(113)=0.021
Å ,
 d(221)=-0,0064 Å ,
 d(501)=0.0025
Å , PbO
2
:
 d(110)=-0.039
Å ,
 d(111)=0.01
Å,
 d(200)=0.006
Å,
 d(113)=0.007
Å.
"samples annealed 650 o
C": 1) PZT rhombohedral perovskite on Si: not available due to dominant pyrochlore content. 2) PZT rhombohedral perovskite on Pt (GIXRD spectrum):
 d(010)=-0,04 Å ,
 d(020)=-0,019 Å 3) PZT rhombohedral perovskite on ITO:
 d(010)=-0,015 Å ,
 d(020)=-0,0001 Å
4) PZT rhombohedral perovskite on Au: not available due to dominant pyrochlore content.
"samples annealed 750 o
C" : 1) PZT rhombohedral perovskite on Si:
 d(010)=-0,029 Å ,
 d(020)=-
0,0006 Å 2) PZT rhombohedral perovskite on Pt:
 d(010)=-0,055 Å ,
 d(020)=-0,0008 Å 3) PZT rhombohedral perovskite on ITO:
 d(010)=-0,0033 Å ,
 d(020)=0,0065 Å 4) PZT rhombohedral perovskite on Au (GIXRD spectrum):
 d(010)=0,019 Å, note PZT(020) peak overlaps with
Au(200).
3. Determination of preferential orientations

The degree of preferential orientation is estimated by calculating the Lotgering factors (ref: F.K.
Lotgering, J. Inorg. Nucl. Chem., 1959, Vol. 9, pp. 113 to 123.) for relevant Bragg peaks. For the
Pt substrate we found f{111} = 0.03, f{200}= 0.07, f{220} = 0.01, f{311}=-0.09. Since a polycristalline film with perfectly random oriented grains film has all f{hkl}=0 while a perfectly
(hkl) oriented film has f{hkl}=1 the determined values which are quite close to f=0 indicate that the
Pt film is polycristalline with nearly randomly oriented grains. The rhombohedral perovskite PZT film on Pt at 750 o
C has a slight {010} preferential orientation as can be seen from the PZT
Lotgering factors f{010}= + 0.20 , f{110} = - 0.37, f{111} = -0.04, f{120} = -0.03, f{121} = -0.04.
For the Au electrode we found f(111)= 0.67, f(200) = -0.27, f(220) = -0.19 indicating a pronounced
(111) oriented Au surface. Since in the 2

-

scans the Au(111), PZT(111), the Au(200), PZT(020) and the Au(220) , PZT(220) peaks overlap within ca

2

=0,15 deg (compare JCPDS-ICCD 01-
073-2022 and 00-004-0784) and peak widths where in the range 0,18-0,25 deg it was not possible.
The ITO substrate in the 2

scan (see Fig.1) has very weak ITO peaks even though data was collected during 19 hours. The reason for this is probably the very small ITO film thickness (35 nm). To enhance ITO film peak intensity GIXRD spectra of the substrate were recorded at incidence angle

=4 deg both for the "as furnished" ITO substrate and after annealing at 650 o
C.
The as furnished substrate has still very weak ITO peaks and evaluation of preferential orientations is still difficult. ITO peak intensities increase in the annealed sample. Supposing that annealing only leads to crystallite growth and not to reorientation of crystallites we can try to evaluate ITO preferential orientations from the annealed sample GIXRD spectrum. The Lotgering factors for the
ITO peaks then are: f{400}=0,27, f{222}=-0.30, f{440}= -0.07, f{622}=-0.04. From these values it appears that the ITO film has a slight (400) preferential orientation. We need to take into account that in the GIXRD spectrum the (400) plane is inclined by
 bragg
(400)-

=17,6 deg - 4 deg = 13,6 deg with respect to the sample surface. We also attempted determination of preferential orientations from the 2

-

scan of the annealed ITO sample and in this case got: f{400}=0,16, f{222}=-0.30,

f{440}= 0, f{622}= 0 which again show a slight (400) preferential orientation, in this case with the
(400) oriented parallel to the substrate surface. In conclusion ITO substrates appear to be slightly
(400) oriented.
ITO substrate after annealing 650 o
C 10 min
2500
2000
1500
1000
500
0 ITO substrate as furnished
15 20 25 30 35 40 45
2 theta (deg)
50 55 60
Fig. 2 GIXRD scans for ITO/glass substrate (incidence angle

=4 deg)
The perovksite PZT films annealed both at 650 o
C and 750 o
C on ITO was sligtly (110) oriented. For the 650 o
C annealed film PZT Lotgering factors are: f{010}= 0.042 , f{110} = 0.19, f{111} =-
0.005, f{120} =-0.04, f{121} = -0.02. For the 750 o
C annealed film PZT Lotgering factors are: f{010}= -0.14 , f{110} = +0.30, f{111} = -0.02, f{120} = -0.30, f{121} = 0.004.
The perovskite PZT film on the Si substate had Lotgering factors f{010}= 0.89 , f{110} = -1.07, f{111} = -0.08 , f{121} = -0.093 and thus is highly (010) oriented.
4. Determination of crystallite sizes
Crystallite sizes of pyrochlore and perovskite phases were determined from integral breadth values using the Scherrer method after correction for instrument broadening, were possible using high resolution 2

-

scans. In some cases howevere the peaks were too weak in 2

-

scans and GIXRD scans were used instead for crystallite size determination. Were both measurements from 2

-
 scans and GIXRD are available values are compared and weighted mean values computed.

Note that in case of perovskite only the (010) and (020) peaks were used since these are the only non-split peaks of the identified rhombohedral perovskite phase. All the results are summarised in
Table 1 substrate thermal treatment Pyrochlore crystallite size (nm) perovskite crystallite size (nm)
Si
Si
Pt
Pt
ITO
ITO
650
750
650
750
650
750
Au/Ti 650 o o o o o o o
C process
C process
C process
C process
C process
C process
C process
9±3 (a), 9.3±2 (b) 9±2 (c)
14±2 (a)
12±1 (b)
No pyrochlore
14±2 (b)
No pyrochlore
9.5 ±3 (b)
No perovskite
26±1 (a)
15±1 (a), 20±2 (b)
16±3 (c)
24±2 (a), 19±6 (b)
24±2 (c)
17±5 (a), 16±4 (b)
16±3 (c)
23±6 (a)
N.A. (Perovskite
& Au overlap)
Au/Ti 750 o
C process
14 ± 4 (b)
N.A. (Perovskite
& Au overlap)
Tab.1 crystallite sizes determined for the pyrochlore and perovskite phases in the investigated samples. (a) results from
2

-

scans, (b) results from GIXRD scan, (c) weighted mea of a) and b). If a) and b) differ more than the standard deviations the error of c) is determined as the semi-difference between a) and b) values. In the other cases the error of c) is the statistical error of the weighted mean.