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CVD diamond wires and tips for x-ray detection: growth and characterisation by SEM and micro-Raman spectroscopy.

Proceeding of SPIE Vol. 3484 (1997), p. 195-203

C.Manfredotti, F.Fizzotti, A.Lo Giudice, G.Mucera, P.Polesello, E.Vittone, G. Mariotto#, C.Vinegoni#, E.Cazzanelli@

Experimental Physics Dept., Torino University, INFN-Sez. Torino, INFM-Unità di Torino, via P.Giuria 1, Torino (I)

# Università di Trento, Dipartimento di Fisica, INFM-Unità di Trento, Via Sommarive 14, I-38050 Povo (TN), Italy

@ Università della Calabria, Dipartimento di Fisica, I-87036 Arcavacata di Rende, Italy

Keywords: diamond thin films, HFCVD, Scanning Electron Microscopy, micro-Raman spectroscopy, x-ray detectors

ABSTRACT

We present a systematic study of the growth of polycrystalline diamond thin films on W wires (50-500 mm diameter) and tips by hot filament assisted chemical vapour deposition (HFCVD) for x-ray detection purposes. We carry out correlations between Scanning Electron Microscopy (SEM) observations and micro-Raman (m-R) spectra, while varying different growth parameters (wire and tip diameter, CH4/H2 ratio, working pressure).

SEM observations show a uniform covering of the substrate, with growth rates ranging from 0.5 to 1.5 mm/h. All m-R spectra show a well defined diamond peak at 1330.8-1333.7 cm-1 together with a broad structure at 1400-1600 cm-1 and a luminescence background extending over the whole scanned range (500-2000 cm-1).

A close analysis shows that best quality is obtained with the lowest diameter substrates, at the lowest CH4 concentration and at a low pressure. Some depositions have been studied as x-ray detectors and their sensitivity at low energy and 6 MeV beam evaluated, showing a good response with respect to standard ionisation chambers.