Electronic performance of 2D-UV detectors

Abstract

With the aim of contributing to the development of two-dimensional UV and X-ray detectors, also stimulated to evaluate specific amplification, handling and addressing electronics, we present a 16-pixel matrix sensor based on high quality polycrystalline diamond. Thick polycrystalline diamond specimens, in the 0.2–0.6 mm range, have been used for the tests and the development of the prototype. Crossed 1 mm large chromium strips have then been realized by lithography on the metal deposited on both the two sample surfaces. The single pixel structure of a matrix appears like a metal-diamond-metal vertical device with a volume which is directly related to the diamond thickness (0.2–0.6 mm 3). Initially, to evaluate the sensor-grade quality of the diamond films, each pixel has been characterized by means of: I– V characteristic in the dark and under ns pulsed excimer laser irradiation; linearity with the photon flux; spectral photoresponse in the 200–1000 nm range. The lateral charge collection at the non-illuminated sensing elements has also been measured to estimate the cross-talk between pixels. Successive tests have been devoted to study the whole matrix response by addressing the pixels singly through the realized electronics both in CW and chopped monochromatic UV illumination. The implemented low-noise transimpedance amplifiers (1 V/1 nA) showed a good linearity whereas the bandwidth was limited just to 20 Hz. Finally, the intensity distribution of a 1 × 1 cm 2 monochromatic UV beam, extracted by a xenon discharge lamp source, as acquired by a realized prototype is illustrated and analyzed.