DIAMOND MICROSTRIP DETECTOR

For its radiation hardness and small leakage current, polycrystalline diamond appears an ideal candidate for high-energy detection, such us deep UV and soft X rays sources. In order to use diamond detectors for image sensor and large area applications, charge photo generation and collection in metal diamond metal (MDM) structures needs to be studied in detail. In this context, a CVD diamond microstrip detector has been realized and characterized with respect to its electrical response in the dark and under illumination. A 50-100 mm thick diamond film has been grown by MWCVD according to the procedure reported elsewhere [1]. A microstrip metallic pattern (Ag, Cr) has been made by standard lithography onto the top and bottom surfaces of about 1x1 cm2 diamond slab. Metallic strip width and interspacing range between 40 and 200 mm to allow for an optimised detection of both deep UV (ArF laser, l=193nm, 4.5 mJ per pulse, FWHM=3nm) and soft X rays (8.06 KeV). Each strip is few millimeters long and is connected to a pad on the top surface. In order to measure the photoresponse both in sandwich and planar configuration an identical pattern rotated by 90° has been realized on the bottom surface. The photoelectrical characterization of the device, was performed under UV laser pulses by varying the illuminated area, bias voltage, span of contacts and light intensity.Results show the feasibility of using the photosensor for image acquisition.