1. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 1 Application of Nanotechnologies in High Energy Physics NanoChanT Collaboration M.Cuffiani, G.M.Dallavalle, L.Malferrari, A.Montanari, C.Montanari, F.Odorici (Sezione I.N.F.N. di Bologna e Dipartimento di Fisica di Bologna) R.Angelucci, F.Corticelli, R.Rizzoli, C.Summonte (CNR-IMM Sezione di Bologna)

2. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 2 Examples of nanotechnologies Technologies for processing materials on a nanometric scale: 1-100 nm Big interest in many fields of research: biology, chemistry, science of materials, nano-electronics, etc. Nanoholes, nanochannels Nanowires, nanotubes Masks, dies Contacts, probes Some nano-objects are very actractive if we think to a possible application to a new generation of position particle detectors:

3. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 3 Carbon Nanotubes (CN) SWNT The regular geometry gives excellent mechanical and electrical properties Among the nano-objects great interest is addressed to Carbon Nanotubes (CN): tubes made by a single sheet of graphene (SingleWallNanoTube) or more sheets (MultiWallNanoTube) 1-2 nm

4. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 4 Electrical properties of CN Mainly depend on the curvature axis of the graphene sheet: Stables with temperatures in the range of about 0-300 o K H.Dai, Surf. Sci., 500 (2002) metallic semiconductor

5. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 5 Growing CNs Non catalytic methods (e.g. arc discharge) allow to produce bundles of CN: BUT for position detector applications we need a regular, uniform and reproducible structure...

6. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 6 5  m MWNT on Fe:  nm, L 10  m, A 4x1 cm 2 Straight CN By using catalysts (Fe,Co, Ni) in Chemical Vapor Deposition methods, it is possible to grow straigth CN !! MW:  nm, L 20  m

7. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 7 Nanochannels: Alumina template Anodization of iperpure Aluminum sheets (100-300  m thick ) under controlled conditions produces an oxide (Al 2 O 3, Alumina) with self-organized regular honeycomb structure 100 nm The size and pitch of nanochannels depend on the parameters of the process (voltage, acid type, acid concentration, temperature): pitch: 40 -> 400 nm Among Alumina properties: mechanical strenght good insulator

8. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 8 Growing CN inside Alumina Growth of CN by Chemical Vapor Deposition of an hydrocarbur at 600-800 o C: temperature, gas concentration and duration of the process determine the CN structure (SWNT or MWNT, metallic or semiconductor) Alumina nanochannels can be used to grow CNs, after the deposition of the cathalist (Ni,Fe,Co) at the bottom of each single pore Insulator Metal or semiconductor Carbon Nanotube Al 2 O 3 J.Li et al. PRL 75 (1999)

9. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 9 Ideas for detector applications Active medium Gas filled nanochannels: nano-pixel detectors charged particle Charge transportation channels n-doped Silicon filled nanochannels: nano-pixel detectors Phosphorus layer (  -converter) photon p-doped silicon caps CN array

10. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 10 NanoChanT project Nano Channel Template: TWO nanotechnologies involved: 1.Nanochannels built in the Alumina template with regular and uniform pattern (overall area:1 cm 2 ) 2.Carbon nanotubes grown inside Alumina template Optimize CN properties in order to use them as charge collectors between an active medium and the readout electronics and study the coupling fabrication of a position particle detector which allows to gain at least one order of magnitude in spatial resolution Thin Silicon R/O electronics Basic idea Nanotube array

11. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 11 Nano Channel Active Layer Detector (simplified) Metal pad Carbon nanotubes: diameter 40 nm; pitch 100 nm. p+ Metal pad n+ Metal pad Alumina 100  m thick n-silicon 100  m thick  Coupling of a silicon diode & CNT’s array: verification of charge production and collection efficiency

12. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 12 Coupling of CN with metals Titanium contact for electrical measurements Metals like Titanium, Nichel and Palladium shows affinity and strong interaction with SWNT. Low resistivity ohmic contacts

13. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 13 Nano Channel Active Layer Detector Metallic strips: pitch 500 nm; length 10 mm; area 5·10 3  m 2 R/O electronics: 50 x 100  m 2 ; area 5·10 3  m 2 Same area Carbon nanotubes: diameter 40 nm; pitch 100 nm. p+ n+ & metal pixels pitch 500 nm metal pad Thin CMOS electronics Thin SiO2 Thin Si (5  m) Alumina 50  m thick

14. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 14 Al anodisation tests (1) SEM planar view from the top-edge of the final alumina: pore size 40 nm, pitch 100 nm. 1  m sample is broken by hand

15. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 15 Al anodisation tests (2) SEM cross-section, taken at the alumina-aluminum interface of the same foil. Al2O3 Al 500 nm

16. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 16 Status and perspectives We obtained encouraging results in building the Alumina Nanochannels (100  m thick) with the optimal geometry for our application (pore size 40 nm, pitch 100 nm) NanoChanT project (INFN + CNR) started an R&D study with the aim of improving by one order of magnitude the resolution for a position particle detector, by using nanotechnologies (Carbon Nanotubes grown inside Alumina Nanochannels) We are developing the instrumentation and process tuning to grow CNs Next step towards a detector will be the study of CNs coupling to an active medium

17. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 17 Nano Channel Gas Detector Metallic strips: pitch 500 nm; length 10 mm; area 5·10 3  m 2 Alumina 300  m thick R/O electronics 50 x 100  m 2 ; area 5·10 3  m 2 Silicon 300  m thick Same area Nano channels: diameter 400 nm; pitch 500 nm; Ar filled @ 1 bar. Double-sided processing Metallic contacts Metallic pad

18. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 18 Anodization cell Thermostat Al foil: anode Pt cathode grid Mixer

19. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 19 Alumina processes Substratehigh purity Al foils 100  m thick Pre-anodization degreasing, annealing, surface cleaning and electropolishing AnodizationPt cathode grid electrolytes: - oxalic acid (0.3 M COOH) 2 or - phosphoric acid (0.3 M H 3 PO 4 ) temperature: 0 - 5 °C voltage: 40 – 195 V Post-anodization5% phosphoric acid etching, 30 °C

20. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 20 CNs in Alumina

21. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 21 Two step Alumina growth Two steps anodization: 1 st step: a)formation of a sacrificial alumina layer (>10  m); b)partial removal of the sacrificial alumina layer, up to the target pore size 2 nd step: c)formation of the target alumina thickness; Processes Tuning: direct measurements of growth and etching rates of the alumina layer. Sacrificial layer Partial removing Target thickness

22. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 22 Alumina growth and etching rates Etching @ 10’: pore size 33 nmEtching start: pore size 26 nm Etching @ 20’: pore size 39 nm Etching @ 30’: pore size 49 nm Etching @ 40’: pore size 65 nmEtching @ 50’: pore size 85 nm Rate 4  m/h

23. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 23 Template with phosphoric acid SEM planar view taken from the TOP of an alumina layer obtained in a single step anodization in 0.3M H 3 PO 4 at 190 V, 0 °C. Pore size 100 nm, pitch 300 nm. SEM cross-section taken at the alumina-aluminum interface of the same layer. Barrier oxide at the pore bottom 100 nm thick.

24. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 24 Template from evaporated Al on Si Al film top view Al2O3 top view Al2O3 cross-section Al2O3 top view (pore size 40 nm) Useful to verify Si-Al2O3 coupling. Preliminary results: oxalic acid, single step.

25. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 25 Cobalt electrodeposition Energy Dispersive X-Ray analysis (EDX) along the alumina layer Al wt %Co wt % Top (0 – 27  m)8812 27 – 37  m from the top96.83.2 40 - 50  m from the top982 bottom (50 – 70  m)991 EDX along the alumina layer reveals Co in a decreasing ratio to Al from the top to the bottom. SEM cross-section of 70  m thick alumina layer. Co was electrodeposited at 17 V, 60 mA, 24 °C. Test method: - Co wire anode - Co (II) based electrolyte - dc regime.

26. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 26 Filling/doping CNs

27. A.Montanari8th Topical Seminar on Innovative Part. and Rad. Detectors- Siena 22 Oct 2002 27 FAQ Why don’t use nanowires How much is the conductance on CN How much the resistivity of Aluminum Why don’t try a gas detector How to couple CN with Al 2 O 3 (Schotky barrier) What’s sputtering What’s Raman spectroscopy Diffusion in 10  m of Si