Influence of the metallic contact in extreme-ultraviolet and soft x-ray diamond based Schottky photodiodes

Abstract

X-ray and UV photovoltaic Schottky photodiodes based on single crystal diamond were recently developed at Rome “Tor Vergata” University laboratories. In this work, different rectifying metallic contact materials were thermally evaporated on the oxidized surface of intrinsic single crystal diamond grown by chemical vapor deposition. Their impact on the detection performance in the extreme UV and soft x-ray spectral regions was studied. The electrical characterization of the metal/diamond Schottky junctions was performed at room temperature by measuring the capacitance–voltage characteristics. The diamond photodiodes were then tested both over the extreme UV spectral region from 10 to 60 eV by using He-Ne DC gas discharge as a radiation source and toroidal vacuum monochromator, and in the soft x-ray range from 6 to 20 keV at the Diamond Light Source synchrotron x-ray beam-line in Harwell (UK). In both experimental setups, time response and spectral responsivity were analyzed for all the investigated Schottky contact materials. A good agreement between the experimental data and theoretical results from Monte Carlo simulations is found

Miniaturized microdosimeters as LET monitors: First comparison of calculated and experimental data performed at the 62 MeV/u 12C beam of INFN-LNS with four different detectors

“…This detector operates in sandwich geometry in order to exploit the internal junction electric field. The detector is in practice a p-i-metal structure with the metallic rectifying contact having a Schottky barrier of about 1.2 eV, as deduced from previous experimental studies [22]. For this reason, the particular detector structure used is able to operate without any external applied voltage, as a result of its internal junction electric field.…”

Diamond based integrated detection system for dosimetric and microdosimetric characterization of radiotherapy ion beams

“…Due to the built‐in potential of about 1.3 V at the Cr/intrinsic diamond interface, 36 the device works as a Schottky barrier photodiode and can operate with no external applied bias voltage. The dosimeter, featured by a very thin thickness, was unbiased while a polarizing voltage of +20 V was applied to the microdosimeter to extend the depletion region throughout the whole thickness.…”

A 3-dimensional interdigitated electrode geometry for the enhancement of charge collection efficiency in diamond detectors

“…Both the width and the gap between the electrodes were 10 µm, in order to provide an equivalent sample for direct comparison with the performances of the 3D detector. In the following, this diamond planar detector In both devices, the metal contacts form a Schottky barrier with the CVD diamond surface [20,21], which has a typical effective acceptor concentration of the order of ~10 14 cm -3 , as reported in previous works [22,Ciancaglioni]. An I-V characteristic (not reported here) of the 3D detector showed a linear, symmetric behavior, reaching typical values of 1 pA at ±20 V. Due to the planar geometry of the Cr grooves, the observed trend was attributed to the reverse current associated with the presence of back-to-back Schottky contacts at the electrodes, preventing a direct polarization current flowing through the device.…”