Performance Analysis of Poly- and Nano-Crystalline Performance Analysis of Poly- and Nano-Crystalline Diamond based Photocathodes Diamond based Photocathodes 6 th International Workshop on Ring Imaging Cherenkov Counters (RICH 2007) Stazione Marittima, Trieste, Italy 15 – 20 October 2007 INFN - Sezione di Bari - Via Amendola 173, 70126 Bari (Italy) M. A. Nitti, M. Colasuonno, E. Nappi, A. Valentini
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Performance Analysis of Poly- and Nano-Crystalline Diamond based Photocathodes 6 th International Workshop on Ring Imaging Cherenkov Counters (RICH 2007)
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Performance Analysis of Poly- and Nano-Crystalline Performance Analysis of Poly- and Nano-Crystalline Diamond based PhotocathodesDiamond based Photocathodes
6th International Workshop on Ring Imaging Cherenkov Counters
(RICH 2007)Stazione Marittima, Trieste, Italy
15 – 20 October 2007
INFN - Sezione di Bari - Via Amendola 173, 70126 Bari (Italy)
M. A. Nitti, M. Colasuonno,
E. Nappi, A. Valentini
RICH 2007 - Trieste - 17th October
Maria Angela Nitti (INFN – Sezione di Bari) 2
Other ContributorsOther Contributors
• Diamond growth: F. Bénédic - Laboratoire d’Ingénierie des Matériaux et des Hautes Pressions, UPR1311 CNRS, Universite´ Paris 13, 99 av. J. B. Clément, 93430 Villetaneuse, France –
• Raman spectroscopy: G. Cicala - Istituto di Metodologie Inorganiche e dei Plasmi (IMIP-CNR) – Sezione di Bari - Via Amendola 122/D, 70126 Bari, Italy -
• Surface hydrogenation treatment: E. Milani, G. Prestopino - Dipartimento di Ingegneria Meccanica, Università di Roma “Tor Vergata”, Via del Politecnico 1, 00133 Roma, Italy -
• Surface morphology analysis: E. Fanizza - Dipartimento di Chimica, Università di Bari, Via Orabona 4, 70124 Bari, Italy -
RICH 2007 - Trieste - 17th October
Maria Angela Nitti (INFN – Sezione di Bari) 3
OutlineOutline
External Quantum Efficiency (QE) results, in the range 150-210 nm, of Poly- and Nano-Crystalline Diamond (PCD and NCD) PCs Informations on the Surface Morphology, Bulk Structure and Crystallinity of PCD and NCD films
Diamond FilmsDiamond Films DEPOSITION PARAMETERSDEPOSITION PARAMETERS
Diamond film
Film Thicknes
s(m)
Input Microwave Power
(W)
Total Gas
Pressure(mbar)
Surface Deposition Temperatu
re (° C)
Gas RatioAr/H2/CH4
(%)
GNCD 2.21 600 200 990 96/3/1
PCD 2.09 1000 50 900 0/98/2
NCD 4.18 600 200 890 96/3/1
PolyPoly and nanonanocrystallinecrystalline diamond films were prepared by MWPECVDMWPECVD, at the LIMHP (Laboratoire d’Ingénierie des Materiaux et des Hautes
Pressions) - CNRS-UPR- Paris.
Substrates = square n-doped silicon
(100) of approximately 1 cm2,
ultrasonically abraded during 1h in a
diamond powder suspension (~ 40 μm
grain size).
RICH 2007 - Trieste - 17th October
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External QEExternal QE Comparison with LiteratureComparison with Literature
@ = 150 nm QE(%) < 0.5
LiteratureLiterature
Proceedings SPIE, vol. 4139 San Diego, California (2000)
A.S. Tremsin, O.H.W. Siegmund
&Diamond & Related Materials 14 (2005) 48-53
@ = 150 nm QE(%) = 7
0,01
0,1
1
10
150 160 170 180 190 200 210
GNCDPCDNCD
(nm)
Best photoemission and th
for the
graphitic nanocrystalline diamond film
RICH 2007 - Trieste - 17th October
Maria Angela Nitti (INFN – Sezione di Bari) 7
RAMAN SPECTRA RAMAN SPECTRA of the diamond film photocathodesof the diamond film photocathodes
The PCD film exhibits an intense and narrow diamond peak at 1332 cm-1, and a broad peak at 1550 cm-1 sp3 > sp2
The NCD film exhibits typical peaks at: 1140 and 1470 cm-1 of transpolyacetylene, 1350 and 1580 cm-1 of graphite D and G bands 1332 cm-1 of broad diamond peak sp3 < sp2
The GNCD film presents the typical bulk structure of a graphitic nanocrystalline sample, with peaks at 1350 and 1580 cm-1 of graphite D and G bands, and the low intensity diamond peak at 1332 cm-1 sp3 « sp2
0
5000
1 104
1.5 104
2 104
2.5 104
3 104
3.5 104
4 104
800 1000 1200 1400 1600 1800 2000
GNCD NCD PCD
Raman shift (cm -1) (N. Wada, et al., J.Non Cryst. Solids 35/36 (1980) 543)
RICH 2007 - Trieste - 17th October
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50 100 150 200 250 3000
200
400
600
800
Height /nm
PXL
GNCD
hMAX = 150 nm
50 100 150 200 250 3000
200
400
600
800
Height /nm
PXL
PCD
hMAX = 120 nm
Significant difference in their surface texture
Surface morphology & Surface morphology & Quantum Efficiency of Quantum Efficiency of GNCD and PCD PCsGNCD and PCD PCs
The distribution of heights is
centred at a value of about
150 nm for both samples
The QE is comparable, and the GNCD PC presents a higher th with respect to the PCD one
3D AFM surface image
and distribution of heights of
RRaa = 30.3 = 30.3 nmnm
RRaa = 30.5 = 30.5 nmnm
0,01
0,1
1
10
150 160 170 180 190 200 210
GNCDPCD
(nm)
RICH 2007 - Trieste - 17th October
Maria Angela Nitti (INFN – Sezione di Bari) 9
NCD
50 100 150 200 250 3000
200
400
600
800
PXL
Height /nm
hMAX = 90 nm
Surface morphology & Surface morphology & Quantum Efficiency of Quantum Efficiency of GNCD and NCD PCsGNCD and NCD PCs
Very similar morphology
50 100 150 200 250 3000
200
400
600
800
Height /nm
PXL
GNCD
3D AFM surface image
and distribution of heights of
RRaa = 26.4 = 26.4 nmnm The distribution of heights of the
NCD is centred at smaller value, about 90 nm, than that of the
GNCD
The QE of the NCD results
to be lower
RRaa = 30.3 = 30.3 nmnm
0,01
0,1
1
10
150 160 170 180 190 200 210
GNCDNCD
(nm)
3D AFM surface image
and distribution of heights of
hMAX = 150 nm
RICH 2007 - Trieste - 17th October
Maria Angela Nitti (INFN – Sezione di Bari) 10
50 100 150 200 250 3000
200
400
600
800
Height /nm
PXL
GNCD
hMAX = 150 nm
SCD
@ = 150 nm
SCD QE(%) = 2.5
lower than that of
GNCD, PCD and NCD
PCs
RRaa = 1.8 = 1.8 nmnm
0,01
0,1
1
10
150 160 170 180 190 200 210
GNCD
SCD
(nm)
Surface morphology & Surface morphology & Quantum Efficiency of Quantum Efficiency of GNCD and SCD PCsGNCD and SCD PCs
Diamond films which present: (a) a low distribution of heights
(b) a high distribution of heights most of the electron photo-excitement region is located near to the surface, and so many more photoelectrons can escape from the film
a larger portion of the electron photo-excitement regions is far from the film surface; therefore, many photoelectrons have to travel a too long path before escaping
Lower QE
Higher QE
RICH 2007 - Trieste - 17th October
Maria Angela Nitti (INFN – Sezione di Bari) 13
Dependence ofDependence of the QE on the distribution of heigths the QE on the distribution of heigths