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Diamond photoconductive structures for X-rays beam monitoring

Giovanni Mazzeo 2Giuseppe Prestopino 2Gennaro Conte 2Victor Ralchenko 1

1. General Physics Institute, Vavilov Str. 38, Moscow 117942, Russian Federation
2. DIE University Roma Tre (DIE), Via Vasca Navale, 84, Roma 00146, Italy


Diamond is considered the elective material for electronic devices operating in extreme environments. In particular, its wide band-gap and high thermal conductivity make diamond the best candidate for detectors able to work with UV and X-ray sources. The use of photoconductive CVD diamond devices for monitoring pulsed UV sources in the field of ULSI photolithography and micro-machining has been recently proposed. For such kind of applications the principal request is for a fast and sensitive detector in order to control the photoresist dosimetry. Such kind of application requires not only the intensity but also the position of the beam. The field of position sensitive detectors (PSDs) has recorded many contributions on 1D and 2D detectors based principally on amorphous and crystalline silicon. With the aim of contributing in understanding potentiality and performances of CVD diamond detectors, we propose a 1D-PSD based on the voltage division scheme to be exploited in deep-UV and X-ray beam centring and monitoring.
High quality, 8x8 mm2 large and 0.8 mm thick, polycrystalline diamond deposited by a microwave CVD process has been used in this work. Chromium deposits have been realized by physical vapour deposition. Fine line lithography has been then used to define structures with resistance values in the kW range. A Neweks PSX100 ArF laser (4.5 mJ per pulse, FWHM=3 ns, 10-100 Hz) has been preliminary used to test the performance in respect of the lateral sensitivity. The output voltage signals have been recorded by using a Le Croy Wavepro 960 digital sampling oscilloscope. The performance to X-ray irradiation has been tested by using a sealed-off 8.06 keV Copper tube typically used in X-ray diffraction. To improve the signal/noise ratio, the beam has been frequency modulated by using a mechanical iron-modified chopper. We present and discuss the results in the framework of the photoconductive response of 1D-PSD as a function of beam dimension and intensity.


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Related papers

Presentation: poster at E-MRS Fall Meeting 2004, Symposium D, by Gennaro Conte
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-05-18 11:54
Revised:   2009-06-08 12:55