Pulsed laser fabrication of 3D diamond sensors

Abstract

3D detectors, whose electrodes extend perpendicularly to the sensor surface, represent one of the solution proposed for the challenges of radiation-harsh environments in high energy physics [1][2][3][4]. We report on the fabrication and characterization of prototypes of 3D diamond detector, which add to the 3D architecture the advantages of diamond as a sensor for tracking purposes. Two different laser sources, a Nd:YAG 1064 Q-switched laser with 8 ns pulse-width and a Ti:sapphire laser source with 30 fs pulse duration have been used to fabricate arrays of graphitic columns in the bulk of a polycrystalline and a single crystal diamond sample. The columns are staggered and connected to graphitic combs which have been fabricated as well by laser irradiation and used as electric contacts. On each sample, an identical pattern of graphitic combs without columns (2D structure) has also been fabricated as a reference. The charge collection efficiency of each 3D sensor has been measured at different voltages and compared with the corresponding 2D structures. The much lower saturation voltages of the 3D sensors compared to those of the planar ones confirm that charge collection takes place at the columnar electrodes. Moreover, an efficiency of 100% is assured by the sensors fabricated with the fslaser source, while a loss in efficiency up to 30% is observed with the sensors fabricated with the ns-laser. The expected behaviour of 3D diamond sensors after strong radiation damage is discussed.

Investigation of 3D diamond detector dosimetric characteristics

“…The presence of boundaries and trapping impurities, decreases the charge collection efficiency compared to a single crystal diamond. In different works it has been demonstrated that the charge collection efficiency of a polycrystalline diamond detector ranges from 0.1 to 0.6 the charge collection efficiency of a single crystal diamond detector [14,15]. Furthermore, the sensitivity depends also on the applied bias voltage as well as on the detector leakage current, therefore the obtained sensitivity value is compatible with the expectations for a pCVD diamond device.…”

Micro-beam and pulsed laser beam techniques for the micro-fabrication of diamond surface and bulk structures

“…The concept of three-dimensional detectors has been conceived for silicon detectors [22] in order to improve the radiation resistance of solid state detectors. In the last years the concept has been also applied to diamond [21,23,24], exploiting the pulsed laser writing techniques made available in the meantime, mainly for optical applications [8].…”

∆E/∆E Measurements of Energetic Ions Using CVD Diamond Detectors

“…Its consistent application in radiation sensing occurred after synthetic chemical vapor deposition (CVD) growth of diamond was demonstrated to produce consistent and suitable properties [5,6]. Since then, diamond detectors have been explored for use in extreme environments [7][8][9][10][11], microdosimetry [12,13], and thermal [10,14,15] and fast neutron sensing [10,[16][17][18][19][20], including deuteriumdeuterium (DD) and deuterium-tritium (DT) fusion plasma diagnostics [21,22]. One extreme environment under consideration for diamond detectors is high-rate particle tracking sensors at the LHC [7,[23][24][25][26].…”