Photon Detector Research at Helsinki Institute of Physics (HIP) and at Ruder Boskovic Institute (RBI)

In this report we describe a design, fabrication process and characterization of photon detectors made of bulk Cadmium Telluride (CdTe) crystals, silicon drift detectors (SDD) and silicon detectors attached with conversion layer scintillator materials (SiS). The Si wafer and chip-scale CdTe detector processing with related interconnection processing was carried out in clean room premises of Micronova center in Espoo, Finland. Unlike Si wafers, CdTe processing must be carried out at the temperatures lower than 150^◦C. Thus, we have developed a low temperature passivation layer processes of aluminum oxide (Al2O3) grown by Atomic Layer Deposition (ALD) method. The CdTe crystals of the size of 10 × 10 × 1mm³ were patterned with proximity-contactless photo-lithography techniques. The detector properties were characterized by IV-CV, Transient Current Technique (TCT) and scanning micrometer precision proton beam methods. The experimental results were verified with TCAD simulations with appropriate defect and material parameters.