Investigating the Sensitivity of CVD Diamond Detectors with Synchrotron Microbeam Mapping

In this project sensitivity mapping using a source of focused X-ray microbeam was performed on three fabricated samples (VS-Pt, HPS-Pt and HPS-Al/Pt). The VS-Pt sample was chosen due to its special features such as thin nitrogen lines and substrate area. The source of focused X-ray beam (from synchrotron micro-beam called Diamond Light Source, DLS) was investigated in order to choose the optimum conditions to obtain high resolution images of the nitrogen lines within the sample. Additionally the sensitivity mapping of HPS-Pt and HPS-Al/Pt was investigated to study the effect of beam size, step displacement, bias polarity, annealing, and electrical contact were studied on the homogeneity of current response in order to choose optimum conditions for synchrotron measurements. High spatial resolution maps obtained for VS-Pt sample with a micro step displacement of 10 μm or less. Photocurrent is affected by bias polarity; current at negative bias is higher than at positive bias. There are regions with high current thus taking more time to restore to baseline value. Time rises slowly near nitrogen line with stabilization time increasing with bias. For HPS-Al/Pt, as bias increases, homogeneity of current response does not improve. At different negative biases, HPS-Al/Pt exhibits high dark current, unstable signals, and very low photocurrent. For HPS-Pt, at a bias of +50 and –50 V, current response is uniform becoming more homogenous at 100 V, and improving further as the bias increases up to +200 V; making it the most suitable choice for synchrotron measurements.