Fabrication and Characterization of X-Ray Spectroscopic Imaging Arrays Based on Thick Single-Crystal CdTe Epitaxial Layers

We present the design and fabrication details of X-ray spectroscopic imaging arrays using metalorganic-vapor-phase-epitaxy-grown thick single-crystal CdTe layers on an n⁺-Si substrate. Each pixel in the array consists of a p-CdTe/n-CdTe/n⁺-Si heterojunction diode structure, which was fabricated by subsequently growing n- and p-CdTe layers on the n⁺-Si substrate. A mechanical dicing process using a diamond blade was used to make deep cuts on the p-CdTe side to define the pixels in an (8 × 8) array. We further developed a low-temperature conductive-epoxy-based bonding technique to bond the array to the readout electronic circuit via an interface board. Preliminary evaluation shows that the array fabrication technique and the bonding technique work good, and the array is capable of discriminating energies of the incident photon and can be applied for the energy-discriminating imaging purpose.