Thesis Defence

GROWTH AND CHARACTERIZATION OF BaZrO3 THIN FILMS FOR MICROWAVE COMMUNICATION APPLICATIONS V. RAJASEKARAKUMAR

MATERIALS RESEARCH CENTER INDIAN INSTITUTE OF SCIENCE BANGALORE- 560012 INDIA

Plan of the presentation
Objectives
Applications
Processing Technique
Structural Properties
SIMS Analysis
AC Electrical Properties
DC Electrical Properties
Future work plan

Objectives
To identify a new material for microwave communication application
To study the dielectric properties of paraelectric thin films and identify the extrinsic loss mechanisms that degrade the material Properties. Processing (PLD)



Thin film structure

 Microwave dielectric properties

Applications


Components used in microwave communications Dielectric resonators Phased array antennas Transmission lines

Phase shifters Band pass filters Coplanar wave guides


Material requirement for microwave dielectrics 1) High dielectric constant, εr 2) Low loss tangent/ high quality factor Q= (tanδ) -1 Q> 10,000 3) Very low temperature coeff. Of resonance TCω= -( 1/2 TC ε + αL ) ~ few ppm/ K High εr →Miniaturization Low loss and Stability (f, TC) → Improved performance

Importance of BaZrO3 High dielectric constant Paraelectric material Low tanδ values High tunability PHYSICAL PROPERTIES OF BaZrO3 Crystalline Structure

Cubic

Lattice Constant (R.T), a

4.192 Å

Color

white

Average Grain Size

~ 1 to 20 µm

Theoretical Density

6.242 g/ cc

Typical Density

5.35-5.95 g/cc

Melting Point

~ 2600 °C

Dielectric Constant, R.T

~110

Pulsed laser deposition system assembly Stepper motor drive Quartz vacuum port KrF Excimer Laser

UV Grade lens

27kV 10Hz 248 nm 600mJ Thermocouple connected to temperature controller

Rotating target

Substrate holder and heater assembly

Deposition Chamber

STRUCTURAL PROPERTIES

Structure and Stoichiometry Effect of substrate temperature in the crystallinity

*

(220)

(211)

(200) PtKα

Intensity (arb. unit)

* PtK β

(111)

*

(110)


BZ Films were grown at different substrate

0

650 C

*

0

600 C 0

550 C

*

pow 20

30

40

2θ

50

60

temperature at a constant partial pressure of 50 mTorr.
The perovskite phase evolves at 5500C and at 6000C the enhancement of (110), (111) and (211) planes are observed.
All the single phase BZ thin films exhibited polycrystalline nature for the thin films deposited upto 6000C.
Further increment of substrate temperature to 6500C, there is a tendency for the orientation along (110) direction with the disappearance of other prominent perovskite peaks.
This is accordance with the Thorton’s model which suggests that at higher substrate temperatures the thin films tend to exhibit columnar structure and higher orientation along a favourable plane.


The BZ thin films deposited at the substrate temperature of 4000C in the pressure of 20 mTorr and subsequently annealed at different temperatures for 90 minutes.
The perovskite peak enhanced with increasing of temperatures upto 7750C.

0

800 C

(220)

0

775 C

Effect of deposition pressure in crystallinity

0

750 C 50

60

Intensity (arb.unit)


The BZ thin films deposited at the substrate temperature of 4000C with various oxygen partial pressure and ex-situ annealed at 7750C for 60 min.

(110)

2θ

0

775 C_60 min

100 mTorr

(211)

40

(200)

30

PtKα

20

PtKβ

(211)

90 min_ 20 mTorr PtKβ

(200)

PtKα

PtKβ

Intensity(arb.unit)

(110)

Effect of ex-situ annealing temperature in crystallinity

50 mTorr

20 mTorr 20

30

40

50

2θ

60

90min

(220)

(211)

(200)

PtKα

PtKβ

Intensity (arb.unit)

(110)

Effect of annealing time in crystallinity

75min 60min 45min. 30 min 20

30

40

50

2θ

60


The BZ thin films deposited at the substrate temperature of 4000C with the oxygen partial pressure of 50 mTorr and ex-situ annealed at 7750C for various time period.

Stress Analysis Stress Vs Annealing temperature

Stress Vs Deposition Pressure

Stress = -Ed0/(2ν(d-d0))

-30

90min._20 mTorr

-45 -50 -55 -60 750

760

770

780

790

800

0

Temperature( C)

Stress (GPa)

E = modulus of elasticity ν= Poisson’s ratio d0 = Actual d- value (JCPDS) d = XRD d- value

-40

-50 -51 -52 -53 -54 -55 -56 -57 -58

0

775 C_60min.

20

40

60

80

100

Pressure (m torr)

Stress Vs Annealing time -40 0

775 C_50mTorr -45 Stress (Gpa)

Stress(GPa)

-35

-50 -55 -60

Ref:

-65 30

40

50

60

70

80

Annealing Time (min)

90

P. Patasalas, J. Appl.Phys. 86, 5296 (1999).

Surface Morphology of BZ thin films deposited at different Substrate temperatures.
The surface morphology of the BZ thin films deposited at different substrate temperatures showed a dense grain structure. Substrate temperature:5500C

Substrate temperature:6000C

Cross sectional View of the BZ thin film


The cross sectional view of the BZ thin film showed multigrain structure.

In-situ grown BZ thin film

Cross sectional view

Surface morphology

Ex- situ grown BZ thin film

Cross sectional view

Surface morphology

Secondary Ion Mass Spectrometry Analysis (SIMS)

Principle Secondary Ion Mass spectrometry (SIMS) works under the principle of mass spectrometry. Capabilities:  Depth resolution of 20- 50 oA with sputter rates down to 1 oA/ sec.  Profiling to a depth of 8µm.  Excellent detection sensitivity with wide dynamic range.  Complete coverage of the periodic table.  Quantification with appropriate standards  Ability to perform imaging to determine the spatial distribution of species or map devices on 2- 5µm scale.  Mass spectra acquisition upto 500 amu.  Isotopic measurements

As- measured signal intensity Vs elapsed errosion time of a BZ thin film 10

5

10

4

10

3

10

2

10

1

10

0

2 -> 16O 4 -> 195Pt 3 -> 90Zr 1 -> 138Ba

1

[C/S]

The crater depth for the BZ thin film which was measured using the Sloan 3030 surface profilometer

2 3

4

0

500

1000 1500 2000 2500

Sput.Time:[S]

Thickness= (Depth/ Total Sputt. Time) x Erosion time Depth: 7976 A0

Depth profile of in-situ annealed BZ thin film using SIMS. 5

10

1 -> 138Ba 2 -> 16O 3 -> 90Zr 4 -> 195Pt

2

*

1 4

10

* *

2 3

10

[C/s]

3 4

2

10

4

3

1

10

1

Tp 0

10

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Thickness (µm)

Type of deposition : In-situ Oxygen partial pressure: 50 mTorr Annealing temperature : 650 0 C


The interface is sharp and almost no diffusion of Ba and Zr in to platinum layer when compared to the thickness of the platinum layer.
The peaks (*) observed in all elements (Ba, Zr, O) reveals that there is a fixed proportion of the constituent species of the expected phase. So the film growth at the interface is good. Moreover, the stoichiometry and sputtering rate are different at the interface which has lead to humps in the region.
Oxygen concentration increases after platinum layer because we have an inter-face of (Pt/ TiO2/ SiO2/ Si) in our substrate.
Tp shows the thickness of the platinum layer (0.18 µm).

Depth profile of Ex-situ annealed BZ thin film using SIMS. 5

10

1 -> 138Ba 2 -> 16O 3 -> 90Zr 4 -> 195Pt

#

1

2

*

4

10

4 2 3

10

*

[C/s]

3 2

4

10

1 1

10

0

10

0.0

0.2

0.4

0.6

0.8

1.0

Thickness (µm)

Deposition pressure : 50 mTorr Substrate temperature : 400 0 C Annealing time : 90 min. Annealing temperature: 600 0 C


The interface is not sharp and all the elements are interdiffused.
In the (*) region both Zr and Oxygen have a uniform rise, whereas Ba falls down suddenly ( Zirconium oxide have formed or segregated).
Hump in the * region due to interface effects.
Flat nature was observed in the region (//). It has given the conclusion of compound formation (ZrO2) at the interface, a flat nature reveals that we have constituents species of definite proportion.
In # area there is a hump in oxygen, that due to TiO2 interface.
The diffusion length is around 0.16 µm.

Effect of substrate temperature 5

10 1 -> 138Ba 2 -> 16O 3 -> 90Zr 4 -> 195Pt

*

1 4

10

*

1 4

10

**

2

* *

2 3

10

3

3

[C/s]

[C/s]

10

3

4

2

10 2

10

1 -> 138Ba 2 -> 16O 3 -> 90Zr 4 -> 195Pt

2

4

4

3

1

10

1

Tp

1

10

0

0.0

0.2

0.4

0.6

0.8

Thickness (µm)

Type of deposition : In-situ Oxygen partial pressure: 50 mTorr Annealing temperature : 550 0 C

10

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Thickness (µm)

Type of deposition : In-situ Oxygen partial pressure: 50 mTorr Annealing temperature : 650 0 C

Effect of ex-situ annealing temperature 5

10

1 -> 138Ba 2 -> 16O 3 -> 90Zr 4 -> 195Pt

#

1

2

*

4

10

4 2 3

10

*

[C/s]

3 2

4

10

1 1

10

0

10

0.0

0.2

0.4

0.6

0.8

1.0

Thickness (µm)

Deposition pressure : 50 mTorr Substrate temperature : 400 0 C Annealing time : 90 min. Annealing temperature : 600 0 C

 In the (*) region both Zr and oxygen have a uniform rise, whereas Ba falls down suddenly ( Zirconium oxide have formed or segregated).  Hump in the * region due to interface effects.  Flat nature was observed in the region “ //”, it has given the conclusion of compound formation (ZrO2) at the interface.  The flat nature reveals that we have constituents species of definite proportion.  In # area there is a hump in oxygen, that due to TiO2 interface.  The diffusion length: 0.161µm

Deposition Pressure Substrate temperature Annealing time Annealing temperature

: 50 mTorr : 400 0 C : 90 min. : 650 0 C

Deposition pressure Substrate temperature Annealing time Annealing temperature

: 50 mTorr : 400 0 C : 90 min. : 775 0 C

5

5

10

10

1

2

4

10

1 -> 138Ba 2 -> 16O 3 -> 90Zr 4 -> 195Pt

1-> 138Ba 2-> 16O 3-> 90Zr 4-> 193Pt

2

2

3

3

10

10

[C/s]

4 3

[C/s]

1

4

10

3 2

2

10

10

4

4

1 1

1

10

0

10

10

0

10

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

Thickness (µm )

Diffusion length: 0.190 µm

0.0

0.5

1.0

1.5

Thickness (µm)

Diffusion length: 0.386 µm


The formation of ZrO2 has decreased with increase of annealing temperature.
The interdiffusion has been take place and the diffusion length has increased with increasing annealing temperature.

Conclusion:

 In the (*) region both Zr and oxygen have a uniform rise, whereas Ba falls down suddenly ( Zirconium oxide have formed or segregated).  Hump in the * region due to interface effects.  Flat nature was observed in the region “ //”, it has given the conclusion of compound formation (ZrO2) at the interface.  The flat nature reveals that we have constituents species of definite proportion.  In # area there is a hump in oxygen, that due to TiO2 interface.  The formation of ZrO2 has decreased with increase of annealing temperature.  The interdiffusion has been take place and the diffusion length has increased with increasing annealing temperature. The flat nature has reduced with increasing annealing temperature, which may be due to dissociation and redistribution of zirconium oxide  The oxygen content increases at the interface of the film which has annealed at 775 0 C. It’s due to the high temperature annealing and the dissociation and redistribution of zirconium oxide  The flatness observed has almost disappeared in the case of annealing temperature 775 0 C, which due to the redistribution of ZrO2 at higher temperatures.

Effect of Oxygen Pressure 5

5

10

10

1 -> 138Ba 2 -> 16O 3 -> 90Zr 4 -> 195Pt

2

* 4 * * *

1

2 3

10

[C/s]

3

4

1

10

4 3

10

2

[C/s]

4

10

1 -> 138Ba 2 -> 16O 3 -> 90Zr 4 -> 195Pt

2

1

*

3

3 2

10

2

10

4

4 1 1

10

1

10

0

10

0

10

0.0

0.0

0.2

0.4

0.6

thickness( µm)

Substrate temperature : 400 0 C Annealing temperature: 775 0 C Annealing time : 90 min. Deposition pressure : 20 mTorr

0.8

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

Thickness(µm)

Substrate temperature : 400 0 C Annealing temperature : 775 0 C Annealing time : 90 min. Deposition pressure : 50 mTorr

5

10

2

1 4

10

1 -> 138Ba 2 -> 16O 3 -> 90Zr 4 -> 195Pt

4 2

3

10

[C/s]

3 2

10

4 1

1

10

0

10

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

Thickness (µm)

Substrate temperature Annealing temperature Annealing time Deposition pressure

: 400 0 C : 775 0 C : 90 min. : 100 mTorr

Conclusion: At the end of the interface, that is almost the end of platinum depth (marked as *), there is a rise in all the element which is almost in a fixed proportion. But really Ti, Zr, Pt are hiked in this right interface zone and the counts are not due to Ba species. It’s due to the mass interference. The sum of masses of Ti and Zr will equal that of Ba.  The profiles doesn’t show any significant variation as a function of oxygen pressure other than the increase of oxygen content at the interface.

Summary  SIMS analysis has given a complete information regarding the interface studies to a high resolution of almost 1nm. In-situ annealed films have a very sharp interface and diffusion of platinum electrode into the film is not found  Ex-situ annealed films have the interdiffusion of both the film and the platinum.  In the ex-situ annealed films the segregation of ZrO2 has been found and which has also dislocated on higher annealing temperatures.  The platinum diffusion into the film has caused an increase of leakage current  The diffusion curve which follows a Gaussian nature is not a perfect Gaussian in the case of interdiffusion of BZ thin films.  The diffusion length of the platinum into the film is found to be higher on higher annealing temperatures as expected  Due to the presence of oxide interfaces ( Pt/ TiO2/ SiO2/ Si) in the substrate the diffusion of the constituent atoms (Ba, Zr, O) present in the film is not well enhanced even on higher annealing temperatures.

AC Electrical Properties

Dielectric Response Real part of dielectric constant as a function of frequency at various temp.

Real part of dielectric constant as a function of temp. at various frequency.

90 80

T= T= T= T= T= T= T=

70 60

ε'

40

0.1K 1K 10K 100K

70 60

ε'

50

80

125 175 200 225 250 275 300

50 40

30

30 20 20 10

2

10

3

10

4

10

0

50

100

150

200

250

300

5

Frequency(Hz)


Dispersion at low frequency
Reduction of ε´ with ↑ frequency
Slope = 0.24 in the range of 100-10kHz.
Slope ↑ with ↑ of temperature

0

Temp( C)


The frequency dispersion ← low frequency space charge accumulation
Dispersion ↑ with ↑ of temp.& extended- hopping of e-charges.

Imaginary part of dielectric constant as a function of frequency at various temp.

Dielectric constant and tan δ dispersion With frequency at room temperature 100

-1

10

tanδ T= 125 T= 150 T = 175 T= 200 T= 225 T= 250 T= 275 T= 300

ε''

ε'

10

75

tanδ

100

50

1

25 -2

10

2

0.1 10

2

10

3

10

4

10

10

5

3

10

4

10

5

10

frequency (Hz)

Frequency(Hz)

At 100 kHz frequency in room Temperature

⇒

Dielectric constant ⇒ 24.4 Loss factor ⇒0.03

Absence of any noticeable dispersion in ε` & tanδ δ

↔

Good quality BZ thin films.

Slopes of ε`& ε″ ruled out Pure Debye or Maxwell- Wagner

Universal frequency response (Jonscher’s model) ε* = ε`- iε″ ε″ = ε∝+σ σ/iεε0ω + a(T) (iω ωn(T)-1)/ ε0 ε` = ε∝+ sin(n(T)Π Π/2) ωn(T)-1 a(T)/ ε0 ε″ = σ/εε0ω + cos(n(T) Π/2) ωn(T)-1 a(T)/ ε0 0.9 Experimental Linear fit

Experimental Linear fit

0.8

1E-6

a(T)

n(T)

0.7 0.6

1E-7

0.5 0.4

0

50

100

150 0

T ( C)

200

1E-8

0

50

100

150

200

0

T ( C)

↑ a(T) with temp ⇒ ↑ contribution of charge carrier term in ε″

250

Impedance Analysis Imaginary part of the impedance Vs frequency 2.0x10

Imaginary part of the modulus Vs frequency

7

-5

1.5x10

0

7

''

Z (Ω)

1.0x10

7

125 150 175 200 225 250 275 300

5.0x10

6

jω ωC0 ε* = (M*)-1 Y* = (Z*)-1 Y* = jω ωC0σ*

M* =

Z*

T= 125 C 0 T= 150 C 0 T= 175 C 0 T= 200 C 0 T= 225 C 0 T= 250 C 0 T= 275 C 0 T= 300 C

-5

1.0x10

M''

1.5x10

T= T= T= T= T= T= T= T=

-6

5.0x10

0.0

0.0 2

10

2

10

3

10

4

10

5

Frequency (Hz)


Non-coincidence of peak frequency of Z″ and M″ ⇒ Non Debye type relaxation phenomenon.

10

3

10

4

10

5

10

Frequency (Hz)


Peak found to shift with increase of temperature towards high frequency ⇒ Single RC combination

This type of asymmetric behavior in real materials largely determined by the Johnscher’s power law

AC conductivity Ac conductivity plot as a function of frequency for different sample temperatures
The plot at low temperature

T= 100 T=150 T= 175 T= 200 T= 225 T= 250 T= 275 T= 300

-7

10

-8

σ ac (Ω.cm)

-1

10

-9

10

-10

10

2

10

3

10

Frequency(Hz)

4

10

5

10

respond to the power law.
The power law dependency corresponds to the short range hopping of charge carriers through trap sites separated by energy barriers of varied heights.
The plot for the different temperature at high frequency region converges with one another, since the electronic conduction which is dominant in that region is independent of frequency.

Arrhenius plot of ac conductivity Vs (1000/T) in BZ thin film.
The plot contain two different regions corresponds -7

LnσT(ω) (S.cm-1)

10

10kHz -8

10

1kHz

-9

10

1.5

0.1kHz

2.0

2.5

3.0 -1

1000/T (K )

to two different activation energies.
At lower temperature the obtained σac is independent of temperature upto 1270C. It’s probably due to the saturation in the number of liberated electrons from the donor states.
Beyond 1270C, the shape of the curve becomes more steeper and linear with the calculated activation energy of 1.3 eV. This might be attributed either to the oxygen vacancy motion or due to the deep trap space charge conduction mechanism.
The activation energy was considerably lower than the band gap energy, which implies that the conduction in this range of temperatures were dominated by the 3.5 charge carriers other than electrons, possibly by ionic charge carriers such as oxygen vacancies.
The non linear shape of the Arrhenius plot indicated that, at different temperatures different mechanisms involved in the ac conduction process.

DC Electrical Properties

DC Leakage Current Characteristics

(Current(amp))

0.1 T= 30 T= 60 T= 75 T= 100 T= 125 T= 150 T= 175 T= 200

1E-4

1E-7

1E-10

VTFL

1E-13 0.1

1

10

(voltage(V)) VTFL → voltage at which the traps get filled

Schottky verification

-2

10

-6

10

0

125 C 0 150 C 0 175 C 0 200 C

1E-5

-10

0.0

1.5 V-> 2.07 eV 2.0 V-> 2.27 eV 3.0 V-> 2.33 eV 4.0 V-> 2.36 eV 5.0 V-> 2.43 eV

2 2

10

T= T= T= T=

1E-6

2

2

ln (J/T ) (A/Cm K )

2

lnJ (A/cm )

10

2

2.0x10

E

1/2

4.0x10

2

6.0x10

2

8.0x10

1/2

[(V/cm) ]


J = AT2 exp( -(ϕ0 - βE1/2)/ κT )
β = ( e3/ Πε0K)1/2 Conditions: I) J Vs E1/2 must be a st. line. The slope = β ii) K from β must ≡ original K iii) ∆E should ↓ with ↑ E

2

1E-7

1E-8

2.2

2.4

2.6

2.8

3.0

-1

1000/T (K )

Results: i) Absence of St. line ii) The original K value is two order less than the calculated one. iii) ∆E & E relation is just opposite.

Possibility of Schottky mechanism & pool Frenkel ruled out.

Space Charge Conduction The Lampert triangle in the J-V plot at room temperature. 0.1

logJ

1E-3

III

1E-5

0 2.

7.1 1E-7

0.98 1E-9 0.1

I

1

10

II


Pure Space Charge → Square law dependence
Modified by bulk generated charges.- due to existing e- to compensate Oxy. Vac. Or thermally excited valance band e-.
These Charges- screen the excess injected ch..
Space charge⇒ no. of injected charges ↑ already existing charges.
These charges ⇒ linear nature if there is a ohmic contact.
> VTFL the space charge Limited Current Predominates and follow power law: I ∝ V2.

logV

Region I → slope = 0.98 Region II → slope = 7.1 Region III → slope = 2.0 ⇓ Lampert’s Triangle

DC Leakage Current Characteristics

Arrhenius plot of conductivity

1E-4 0

Current (amp)

1E-6

T= 100 C 0 T= 125 C 0 T= 150 C 0 T= 175 C 0 T= 200 C

1E-11

1E-7

II

1E-8

ln(J/E)

1E-5

0.9 9e V

1E-9 1E-10

I

1E-11 1

10

voltage (V)

1E-12 2.1

2.2

2.3

2.4

1000/T


The linear region ( I)- obey the Arrhenius equation: J~ exp( -∆E/ κT) ∆E → Activation Energy κ → Boltzmann constant
∆E = 0.99 eV. → hopping of oxygen vacancy
Waser → A.E for oxygen. V. = 1eV.

2.5

Trap filled voltage as a function of temperature 16

VTFL (V)

12

8

4 0

50

100

150

200


VTFL→ A voltage where the Fermi energy level would increase well above all deep trap levels.
All traps filled > the TFL at a given temperature
While ↑ temp., some of the filled traps would reemit e- s ⇒ the trap site would become empty ⇒ ↑ VTFL with ↑temp.
Upto 1250C → follows Lampert’s Space charge law.( mainly considered on conduction by electronic charges.)
To establish equilibrium of charges in the bulk of the thin film, reasonable time is required – trapping and detrapping would limit the distribution

0

Temperature ( C)

Detrapping rate Trapping rate Tt→c = υNtNc exp(-∆E/κT) Tc→t = NcNtσt υ→ Attempt frequency of e- to escape N→ Density of unoccupied energy states from the trap. σ → Capture Cross Section of the traps ∆E → Energy difference. Lower temperature
Very few e- in the upper energy stateNo much variation in trapping rate
Entire process limited by detrapping.

At Higher temp
Significant amount of e- in C-band⇒↑ trapping rate & it overshadow detrapping.
⇒ no. of e- required to fill trap is less.

80

0.1K 1K 10K 100K

70

ε'

60

Some extrinsic effect such as charge carrier contribution

50 40 30 20

0

50

100

150

200

250

300

0

Temp( C)

ε* = ε`- iε″ ε″ = ε∝+σ σ/iεε0ω + a(T) (iω ωn(T)-1)/ ε0 ε` = ε∝+ sin(n(T)Π Π/2) ωn(T)-1 a(T)/ ε0 ε″ = σ/εε0ω + cos(n(T) Π/2) ωn(T)-1 a(T)/ ε0

n(T) ⇒ dipole interaction A(T) ⇒ strength of polarisability

N(T) = 1 there is no interaction (gas and liguid) N(T) decreases with temp. ⇒ ↑ dipole interaction ↑ a(T) with temp ⇒ ↑ contribution of charge carrier term in ε″(sigma) Pool Frenkel: ln (J/E) vs. E1/2 Ln (J/E) vs. 1/T ⇒ st. line

Summary
XRD showed the crystallinity of the BZ thin film and there was no secondary phases formation.
Surface morphology showed a dense grain structure.
SIMS revealed that the in-situ deposited films had a sharp interface and the same time the ex-situ films had a interdiffusion
Dielectric responses ruled out the possibility of Pure Debye or Maxwell- Wagner type relaxation and found to obey the universal frequency response (Jonscher’s model)
Complex impedance and Modulus studies revealed the presence of single parallel RC circuit.
Films of the BZ exhibited a space charge limited dc leakage current.

Plan for the Future work
The ac electrical studies can be extended to the microwave frequency regime to understand the material behavior
The BZ thin films could be grown on different substrates and the substrate with different orientation to correlate structure with electrical properties. The cross sectional TEM and the glancing angle XRD studies could be useful to get more information about the substrate and the film orientation.
The diffusion studies through SIMS could be done on the epitaxial BZ thin films and correlate with the leakage current behavior, for the better understanding of the leakage current mechanism.
Correlating the cross sectional TEM and the SIMS profile results can lead to a better understanding of growth process, as well as defect chemistry.
Studies related to the formation and mobility of protonic charge carriers will be useful in proton conductors.
The usage of different metal and conducting oxide electrodes can enhance the device performance.

ACKNOWLEDGEMENT

Prof. S. B.Krupanidhi Prof. K. Chattopadhyay Prof. T. R. N. Kutty Prof. K.B.R.Varma Dr. A. K. Tyagi, Dr. S.Rajagopalan, Dr. Sornadurai, IGCAR, Kalpakkam. Dr. Bharadwaja, Dr. Sanjeeb Saha, Dr. Sudipta Bhattacharya, Mr. P. Victor Louis Arokiyaraj, Mr. Apurba Laha, Mr. Venkateshwaralu Mr. Ranjith, Mr.Thirumalvalavan, Mr. Sameer Shah, Mr. Tripathi, Mr.Manju, Mr.Jayantho, Mr.Dhananjaya, Mr.Asis, Miss. Vanaja. Mr. Krishna, Mr.Gurulinga, Dr. Samphilip, Mr. Kannan, Mr. Sankaranarayana & MRC staffs. Friends: Balu, M.P.Raja,Thiruna, Sevu, Sathya, Guru, Sudakar & R-Gang.

THANKS