Advanced Radiation Detection Devices: 3D Diamond Detectors and KSr2I5:Eu Scintillating Crystals

First, the radiation detection charge collection properties have been determined for four diamonds with each diamond having received a fluence of 1 MeV neutron irradiation. Photoluminescence measurements were conducted at 150 K on the most irradiated diamond, revealing information about the energies of optically-active defect centers created by the neutron radiation. Then, two diamond plates, one single-crystal and the other polycrystalline, were processed using the bulk microstructural modification technique of femtosecond-pulsed laser machining. Deep reactive ion etching of the samples revealed that the laser-treated channels etch considerably faster than the surrounding diamond. Next, to create through-diamond vias (TDVs) in diamond plates, deep reactive ion etching techniques similar to those employed in the silicon industry for creating through-silicon vias were utilized. Two different diamonds, one optical-grade and one detector-grade, were used to establish a repeatable process for etching holes completely through diamond. A stainless steel foil was found to be an effective and robust etching mask for creating TDVs with an aspect ratio of 5.0. Electroplating was used to fill the TDVs with a highly conductive chromium metal. The TDVs were connected with interdigitated strips on the surface of the diamond, establishing for the first time a 3D diamond radiation detector with fully metal electrodes. Lastly, the spatial uniformity of the light emission produced by a relatively new scintillation crystal composed of potassium strontium iodide activated with europium has been explored.