Diamond is a material with outstanding mechanical, electrical and optical properties. Single crystal diamond has a large bandgap (~ 5.47 eV), large atomic displacement energy (~ 43eV), high electric breakdown field (107 V cm-1) and high thermal conductivity at room temperature. All these superior properties make diamond inherently a superb radiation tolerant material for harsh radiation environments. In this study, single crystal diamond (scd) substrates grown at Michigan State University (MSU) by microwave plasma-assisted chemical vapor deposition (MPACVD) are tested to develop detectors for swift heavy ion beam. Prior to beam irradiation, the material properties of the diamond were characterized by UV-VIS spectroscopy and FTIR (Fourier Transform Infrared Spectroscopy). After fabrication of detectors, their performance were tested by irradiating with swift heavy ion (SHI) beams in the range of 100-150 MeV/u at the National Superconducting Cyclotron Laboratory (NSCL) at MSU. In addition to MSU grown samples, commercial electronic grade samples (Microwave Enterprises Ltd.) were also investigated under the same radiation environment. Post irradiation, samples ware characterized by the transient current technique (TCT) to understand how charge transport properties get affected by the beam irradiation. The charge collection efficiency (CCE) and the lifetime of the holes and electrons created were studied. A completely non-irradiated commercially available electronic grade diamond was also tested in the same testing configuration to generate a reference. Beam irradiated samples were also characterized by X-ray diffraction and Raman spectroscopy to characterize for any structural damage. The overall characterizations mostly confirmed a deterioration of charge transport properties. However, any evidence of substantial structural damage by the irradiation could not be found. One relevant observation was that the MSU lab grown diamond had a shorter carrier lifetime primarily due to more nitrogen impurities present in the grown diamond. Next, to improve charge transport performance of MSU lab grown diamond substrates for electronic applications, single crystal diamond was deposited in a low nitrogen environment to grow thick layers (≥ 200 μm). In general, epitaxial growth on surface close to the (001) crystallographic plane at a low nitrogen environment often suffers from defects forming on the surface. Such defects arise from dislocations (already present in the substrate), twining during the growth process. A possible solution to this issue is to grow samples on misoriented substrates (i.e. on surfaces that are slightly tilted from the (001) plane). The resulting surface profile largely depends on the growth condition (i.e. temperature, pressure, methane concentration), as well as the substrate misorientation angle. The deposition on a misoriented surface happens with a step flow growth process. It is found in research literature that impurities present in the deposition gas generally tend to concentrate at steps more than on terrace. Hence the spatial size of the step height and terrace width distribution produced as a result of misorientation angle variation is important for the quality of the deposited diamond. A detailed study of the distribution of step height and terrace width with respect to misorientation angle for thick layers (~ 200 μm) was performed. The step height and terrace width distributions can help decide the selection of offcut angle, doping concentration and growth layer thickness, which otherwise may create localized and non-uniform distribution of impurities and non-uniform breakdown electric fields.
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