On the growth of rare earth doped LiYF4 thin film by pulsed laser
Transcript of On the growth of rare earth doped LiYF4 thin film by pulsed laser
![Page 1: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/1.jpg)
1
Dr. M.Anwar-ul-Haq
On the growth of rare earth doped LiYF4thin films by pulsed laser deposition
Prof. Paola BicchiDr. Stefano Barsanti
Department of Physics,University of Siena, Italy
Department of Physics, University of Sargodha,
Pakistan
International Scientific Spring at NCP from March 01-06, 2010
![Page 2: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/2.jpg)
2
Layout of the presentationIntroduction
Experimental setup
Conclusions
Thin filmsPulsed Laser Deposition (PLD)
ResultsNd3+:LiYF4 thin films
![Page 3: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/3.jpg)
3
Development of rare earth (RE) ions-doped LiYF4
(YLF) fluoride thin films with characteristics suitable for their use as active medium in micro-lasers sources in the 1-2 μm, via Pulsed Laser Deposition (PLD)
Materials used
Aim of the research workIntroduction
SubstratesSubstrates Pure mono-crystalline YLF
TargetsTargets RE ions- doped mono-crystalline YLF
Nd3+ or Tm3+
![Page 4: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/4.jpg)
4
Why thin film in micro-laser area? [1,2]Introduction
[2] C. L. Bonner, A. A. Anderson, R. W. Eason, D. P. Shepherd, D. S. Gill, C. Grivas and N. Vainos, Opt. Lett. 22 (1997) 988[1] D. B. Chrisey and G. K. Hubler, (Eds.), Pulsed laser deposition of thin films, John Wiley, New York (1994)
The removal of the heat in excess from the active media
Maximizes the interaction zone between pump and active media
Enhancement of the confinement of the radiations
Reduction of the lasing threshold
The realization of active optical devices in film shape would magnifies all advantages of the micro-lasers systems by favoring;
![Page 5: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/5.jpg)
5
Thin Films [3]
Growth Mechanism [4]
on a suitable substrate or on previously deposited layers
Dimensions from fractions of a nanometer to several micrometers in thickness
Realization
[3] K. Wasa, M. Kitabatake and H. Adachi, Thin film materials technology: sputtering of compound materials, Springer, Heidelberg (2004)[4] A. Rockett, The materials science of semiconductors, Springer, New York (2007)
![Page 6: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/6.jpg)
6
Major ways of thin films growth [5]Thin films
Volmer-Weber growth(Island growth)
Stranski-Krastinov growth(mixed growth)
Frank-van de Merwe growth(layer by layer growth)
[5] J. A. Venables, G. D. T. Spiller and M. Hanbucken, Rep. Prog. Sci. 47 (1984) 399
![Page 7: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/7.jpg)
7
Liquid Phase EpitaxyThermal EvaporationSputtering
Molecular Beam EpitaxyChemical Vapour DepositionIon Implantation
Pulsed laser deposition
Ejection of materials from the target by highly energetic laser pulses, with subsequent deposition/condensation on a suitable substrate
[1] D. B. Chrisey and G. K. Hubler, (Eds.), Pulsed laser deposition of thin films, John Wiley, New York (1994)
Thin film growth techniques [1]Thin films
![Page 8: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/8.jpg)
8
Typical PLD experimental setup
Interaction of the photons with the target causes material ejection via a thermal and / or electronic process
The ablated plume is a mixture of energetic particles such as atoms, molecules, electrons, ions, sub-microns or micron-sized solid particles and molten globules
[6] P. R. Willmott and J. R. Huber, Rev. Mod. Phys. 72 (2000) 315
Pulsed Laser Deposition (PLD) [1,6]Thin films
[1] D. B. Chrisey and G. K. Hubler, (Eds.), Pulsed laser deposition of thin films, John Wiley, New York (1994)
![Page 9: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/9.jpg)
9
laser external to the ablation/deposition chamber,
flexibility of the experimental set-up,
possibility of getting thin films of almost any kind of material,
deposition can be performed either in vacuum or in presence
of a controlled background atmosphere
stoichiometry in the film can be maintained,
films growth rates can be controlled,
multiple layer films can be grown,
deposition on substrates kept at any temperature, is possible
[7] J. Schou, Appl. Surf. Sci. 255 (2009) 5191
[6] P. R. Willmott and J. R. Huber, Rev. Mod. Phys. 72 (2000) 315
Advantages of PLD [6,7]Thin filmsPLD
![Page 10: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/10.jpg)
10
Crystals doped with rare earth Laser sources in IR
Disadvantages Sensitive to thermal shocks even for slow thermal gradient and to OH¯ radical contamination during growth even a few ppm
OxidesFluorides
Lower phonon energy
Stronger emission cross sectionsAdvantages of fluorides over oxides [8, 9]
Films of RE ions-doped fluorides
Excellent optical properties + Benefits of thin film[8] A. A. Kaminskii, Laser Crystals, Springer-Verlag, New York (1981)
[9] C. Garapon, S. Guy, S. Skasasian, A. Bensalah, C. Champeaux and R. Brenier, Appl. Phys. A 91 (2008) 493
Why fluorides?Thin filmsPLD
![Page 11: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/11.jpg)
11
Weight
Chemical Formula
Properties of YLF crystal [11]
Monoaxis (a, c)Crystallographic axis
no = 1.4485ne = 1.4708Refractive Indexes
3.99 g/cm3Density
0.12- 7.3 µmTransparency
5.07 MohsHardness
819°CMelting Point
TetragonalCrystal Structure
171.8 amu
LiYF4
Unit cell of YLF [10]
Substrate mono-crystalline YLF
Radius ~ 4.7 – 7.2 mm
Thickness ~ 2 mm
[11] R. L. Aggarwal, D. J. Ripin, J. R. Ochoa and T. Y. Fan, J. Appl. Phys. 98 (2005) 103514
[10] E. Garcia and R. R. Ryan, Acta Crystallogr., Sect C 49 (1993) 2053
Substrate materialExperimental
setup
YLF Crystal
Experimental setup
![Page 12: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/12.jpg)
12
2.1 x10201.5
1.4 x10201
Nd3+
N (cm-3)Concentration (at. %)Dopant
Target crystals
NdNd3+3+:LiYF:LiYF44 (Nd:YLF)(Nd:YLF)
Radius ~ 4.7 – 7.2 mm, Thickness ~ 3 mm
Target materialsExperimental
setup
The YLF and Nd:YLF mono-crystals used during our PLD experiments were either grown by the NEST growth facility in Pisa or provided by a commercial supplier (VLOC, USA).
![Page 13: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/13.jpg)
13
Ablation setup Deposition setup
Film growth systemExperimental
setup
![Page 14: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/14.jpg)
14
LaserLaser
PlumePlume
ShutterShutter
Rotating Rotating target holdertarget holder
Substrate heaterSubstrate heater//holderholder
Heater Heater ConnectionsConnections
Photos of the UHV chamberExperimental
setup
Auxiliary Auxiliary viewportsviewportsVacuum gaugesVacuum gaugesGas valveGas valve
Laser entrance Laser entrance windowwindow
![Page 15: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/15.jpg)
15
Knudsen layerAdiabatic expansion
Heated substrate
PLD processExperimental setup
![Page 16: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/16.jpg)
16
Film in-situ analysisExperimental setup
Realization of the film growth
To verify the presence of the rare earth ions in the film
![Page 17: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/17.jpg)
17
CCD camera photo of the Nd:YLF films Experimental
setup
The film was deposited with laser fluency of 10 J/cm2 in 1 Pa of He atmosphere at a substrate temperature of 650 °C.
![Page 18: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/18.jpg)
18
Determining the kind of film deposited
To determine if the orientation from the substrate to the film has been transferred
Surface quality
Concentration of Nd³+ ions present
Film ex-situ characterisationsExperimental setup
![Page 19: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/19.jpg)
19
Simplified level scheme Absorption curve
Simplified level scheme and absorption curve for Nd:YLF [12,13]Experimental
setup
[13] J. R. Ryan and R. Beach, J. Opt. Soc. Am. B:Opt. Phys. 9 (1992) 1883
[12] A. A. S. da Gama, G. F. de Sa, P. Porcher and P. Caro, J. Chem. Phys. 75 (1981) 2583
• The fluorescence profiles of Nd3+-doped YLF crystals depend on they being recorded with E || or E ⊥ to the crystal c-axis [13].
• The Nd3+ 4F3/2 manifold lifetime is concentration dependent in such a way that lower concentrated samples manifest a higher lifetime and vice versa [13].
![Page 20: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/20.jpg)
20
Setup for the ex-situ characterizationExperimental
setup
![Page 21: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/21.jpg)
21
Results
Ablation in vacuum
Ablation in 1 Pa of He
Plume analysisResults
![Page 22: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/22.jpg)
22
Plume analysisResults
• The expansion velocities of the plume species were found reduced in presence of 1 Pa of He.
• Both in vacuum and in 1 Pa of He, the expansion velocity of most of the plume components saturates beyond 8 J/cm2.
• In vacuum, all the plume species were focused along the target normal except lightest neutral Li, which was found to point preferentially at 16° to the target normal.
• In presence of 1 Pa of He, Li and all other plume species were focused along the target normal.
• The FWHM of the angular distribution curves of the plume components was found reduced in 1 Pa of He compared to the similar measurements done in vacuum and gave indication of the confinement of the plume in the presence of 1 Pa of He.
• Ablation threshold in vacuum for all the species was found to be 1.7 ± 0.3 J/cm2 with exception of Li for which 0.7 ± 0.3 J/cm2.
![Page 23: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/23.jpg)
23
Plume shape
(a) Vacuum (b) 1 Pa of He
Results
![Page 24: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/24.jpg)
24
Nd:YLF thin filmsResults
PLD in vacuum
PLD in 1 Pa of He
Low (4 J/cm2) and high (10 J/cm2) laser fluency
Deposition at Ts = 650°C
![Page 25: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/25.jpg)
25
High fluency (10 J/cm2)
Deposition conditionsLaser wavelength 355 nm
Laser fluency 10 J/cm²Ablation time 20’
Repetition rate 10 Hz
Laser Pulse duration 13 ns
Target Nd:YLF 1.5% at.
Substrate YLF
Vacuum 1 1 ××1010--44 PaPa
Target-substrate distance 35 mm
Temperature of the substrate 650°C
Results• Vacuum - Ts=650°C
![Page 26: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/26.jpg)
26
Heating/cooling cycle of the substrate for film depositionResults• Vacuum - Ts=650°C
![Page 27: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/27.jpg)
27
Films in-situ analysis
Realization of the film
Presence of Nd3+ ions in the film
Portion of the LIF spectrum following 355 nm excitation, recorded in the Nd:YLF bulk crystal and from a film grown in vacuum with 10J/cm2 laser fluency.
Example of interference pattern producedby a film deposited in vacuum
Results• Vacuum - Ts=650°C
![Page 28: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/28.jpg)
28
Films ex-situ characterizations
![Page 29: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/29.jpg)
29
4F3/2 → 4I11/2
Unpolarized, normalized, fluorescence spectra
λλexcexc = 806.6 nm= 806.6 nm
4F3/2 → 4I9/2
Crystalline Nd:YF film
Results• Vacuum - Ts=650°C
[14] S. Barsanti, F. Comacchia, A. Di Lieto, A. Toncelli, M. Tonelli and P. Bicchi, Thin Solid Films 516 (2008) 2009
From Ref. [14]
![Page 30: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/30.jpg)
30
Life time measurement of the 4F3/2 manifold
Film deposited at Ts=650°C in vacuum with Fl = 4 J/cm2 [14]
Film deposited at Ts=650°Cin vacuum with Fl = 10 J/cm2
τFilm = 242 ± 5 μs
τTarget = 464 ± 2 μs
[14] S. Barsanti, F. Comacchia, A. Di Lieto, A. Toncelli, M. Tonelli and P. Bicchi, Thin Solid Films 516 (2008) 2009
Results• Vacuum - Ts=650°C
Nd:YF film
![Page 31: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/31.jpg)
31
Deposition in presence of 1 Pa of He
Deposition parameters
85’Ablation time4 J/cm²Laser fluency
355 nmLaser wavelength
10 HzRepetition rate
13 nsLaser Pulse duration
35 mmTarget-substrate distance
650°CTemperature of the substrate
1 Pa of He1 Pa of HeBack ground atmosphere
YLFSubstrate
Nd:YLF 1.5% at.Target
Results• 1 Pa of He - Ts=650°C
![Page 32: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/32.jpg)
32
Unpolarized, normalized, fluorescence spectra
λλexcexc = 806.6 nm= 806.6 nm
4F3/2 → 4I11/24F3/2 → 4I9/2
Crystalline Nd:YLF film
Inhomogeneous
Results• 1 Pa of He - Ts=650°C
![Page 33: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/33.jpg)
33
Average Nd3+ ion concentration in the film greater than in the target
Concentration of Nd3+ ions in the film
Single exponential decay
τFilm average = 437 μs
τTarget = 464 ± 2 μs
4F3/2 manifold lifetime
λλexc exc = 806.6 nm
Variation from point to point ~ ± 10%
Results• 1 Pa of He - Ts=650°C
![Page 34: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/34.jpg)
34
Volmer-Weber growth
Morphological analysisResults• 1 Pa of He - Ts=650°C
![Page 35: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/35.jpg)
35
Deposition conditionsLaser wavelength 355 nm
Laser fluency 10 J/cm²Ablation time 20’
Repetition rate 10 Hz
Laser Pulse duration 13 ns
Target Nd:YLF 1.5% at.
Substrate YLF
Back ground atmosphere 1 Pa of He1 Pa of He
Target-substrate distance 35 mm
Temperature of the substrate 650°C
High fluency (10 J/cm2)Results• 1 Pa of He - Ts=650°C
![Page 36: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/36.jpg)
36
Unpolarized, normalized, fluorescence spectra
λλexcexc = 806.6 nm= 806.6 nm
Crystalline Nd:YLF film
4F3/2 → 4I9/24F3/2 → 4I11/2
Homogeneous
Results• 1 Pa of He - Ts=650°C
![Page 37: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/37.jpg)
37
Optical analysis Optical analysis ⎪⎪⎪⎪ and and ⊥⊥ to to cc--axisaxis
4F3/2 → 4I9/24F3/2 → 4I11/2
The transition of interest for the possible lasing action was favored in the film as much as in the bulk.
Results• 1 Pa of He - Ts=650°C
4F3/2 → 4I9/24F3/2 → 4I11/2
![Page 38: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/38.jpg)
38
Optical analysis Optical analysis ⎪⎪⎪⎪ and and ⊥⊥ to to cc--axisaxis
The global spectral intensity, in both the emissions is higher when E || to c-axis with only exception of
2//
867863
867||863|| ≈⎟⎟⎠
⎞⎜⎜⎝
⎛
⊥⊥ FilmIIII
3//
arg867863
867||863|| ≈⎟⎟⎠
⎞⎜⎜⎝
⎛
⊥⊥ etTIIII
Transition 4F3/2→ 4I9/2
The spectral profile in the film and in the bulk changes in the same way in shifting the polarization from E || to E ⊥to the c-axis.
Results• 1 Pa of He - Ts=650°C
![Page 39: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/39.jpg)
39
Optical analysis Optical analysis ⎪⎪⎪⎪ and and ⊥⊥ to to cc--axisaxis
The only mismatch
( ) 2.1arg10471053 ≈etTII
Transition 4F3/2→ 4I11/2
The spectral profile in the film and in the bulk remains the same in shifting the polarization from E || to E ⊥ to the c-axis.
( ) 2.110531047 ≈FilmII
Some features compatible with a considerable if not complete transfer of orientation from the substrate
to the film
Results• 1 Pa of He - Ts=650°C
![Page 40: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/40.jpg)
40
Concentration of Nd3+ ions in the film
Single exponential decay
τFilm = 468 ± 5 μs
τTarget = 464 ± 2 μs
4F3/2 manifold lifetime
τTarget = τFilm
λλexc exc = 806.6 nm
Same Nd3+ ion concentration in the film and the target
Results• 1 Pa of He - Ts=650°C
![Page 41: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/41.jpg)
41
Morphological analysis
Mixed growth
Results• 1 Pa of He - Ts=650°C
![Page 42: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/42.jpg)
42
Conclusions
In fact in this case:
• The grown film was a crystalline Nd:YLF film.
• It was homogeneous.
• It showed some spectral features compatible with a consistent, even if not complete, transfer of the substrate orientation to the film.
• The concentration of the dopant ions was transferred from the bulk to the film.
• It had a rather good surface quality
The best film produced which showed promising optical qualities to reach the goal of this project was the Nd:YLF one obtained in 1 Pa of He with a laser fluency of 10 J/cm2, when Ts was 650°C.
We succeeded to deposit crystalline YLF films doped with Nd3+.
![Page 43: On the growth of rare earth doped LiYF4 thin film by pulsed laser](https://reader031.fdocuments.in/reader031/viewer/2022021306/6207458f49d709492c2fbbf1/html5/thumbnails/43.jpg)
43
Publications1. P. Bicchi, M. Anwar-ul-Haq and S. Barsanti In: A. N. Camilleri (Ed.),
Radiation Physics Research Progress, ISBN: 978-1-60021-988-8, Nova Science Publishers, Inc., Hauppauge, NY (2008), pg. 193-217.
2. S. Barsanti, M. Anwar-Ul-Haq and R. Bicchi, Thin Solid Films 517 (2009) 2029-2034.
3. M. Anwar-ul-Haq, S. Barsanti, A. Bogi and P. Bicchi, Opt. Mat. 31 (2009) 1860-1863.
4. M. Anwar-ul-Haq, S. Barsanti and P. Bicchi, IEEE NANO 2009, ISBN:978-981-08-3694-8, (2009) 373-376.
5. M. Anwar-ul-Haq, S. Barsanti and P. Bicchi, DGaO Proceedings 2009-Http://www.dgao-proceedings.de, ISSN:1614-8436, (2009) P35.
6. A. Bogi, S. Barsanti, M. Anwar-ul-Haq, P. Bicchi, Appl. Phys. A 98 (2010) 153-159