Energy and position resolution of germanium microstrip detectors at X-ray energies 15 to 100 keV

Germanium offers superior energy and position resolution compared to silicon for the detection of X-rays at energies between 15 and 100 keV. We have characterised 200 μm strip pitch detectors fabricated by two different processes. By scanning a 10 μm wide monochromatic synchrotron X-ray beam across the detectors, measurements were made on both spectral energy response and spatial resolution. Charge diffusion splitting of X-rays absorbed between neighbouring diode strips seriously degraded performance, but by reconstructing events using an energy-sum coincidence algorithm we succeeded in producing artefact-free spectra with energy resolution 2 keV, peak/valley ratios >1000, and <2% count uniformity across the detector surface. The results show remarkable agreement with those predicted by our computer simulation, which combines the EGS4 code for photon absorption with a simple algorithm to account for charge diffusion