Optimization of <= 200μm pitch CZT detectors for future high-resolution x-ray instrumentation in astrophysics

Cadmium Zinc Telluride and Cadmium Telluride are the detector materials of choice for the detection of X-rays in the X-ray energy band E ≥ 5 keV with excellent spatial and spectral resolution and without cryogenic cooling. Owing to recent breakthroughs in grazing incidence mirror technology, next-generation hard X-ray telescopes will achieve angular resolution between 5 and 10 arc seconds - about an order of magnitude better than that of the NuSTAR hard X-ray telescope. As a consequence, the next generation of X-ray telescopes will require pixelated X-ray detectors with pixels on a grid with a lattice constant of ≤ 250 μm. Additional detector requirements include a low energy threshold of less than 5 keV and an energy resolution of less than one keV. The science drivers for a high angular-resolution X-ray mission include studies and measurements of black hole spins, the cosmic evolution of super-massive black holes, active galactic nuclei feedback, and the behaviour of matter at very high densities. In this contribution, we report on our RandD studies with the goal to optimise small-pixel Cadmium Zinc Telluride and Cadmium Telluride detectors.