This thesis concerns the field of cooled infrared detectors used for astrophysical applications. In this field, the DPFT/SMTP (Infrared Laboratory) of CEA-LETI-MINATEC works closely with Lynred, a world leader in the production of high-performance infrared focal planes. In this context, the infrared laboratory is developing new generations of infrared detectors to meet the needs of future products. One of the current development axes concerns the quality of the p-type semiconductor metal interface. These developments are driven by the increase in the operating temperature of the detectors, as well as by the very strong performance requirements for space applications. The challenge of this thesis is to contribute to a better understanding of the chemical species present at the interface of interest as a function of different surface treatment types and to link them to the electrical properties of the contact made. The candidate will join the infrared laboratory, which includes the entire detector production process. He/she will produce these samples using the technological means available in the LETI clean room, in collaboration with experts in the field. He/she will also have access to the necessary characterization tools (SIMS, XPS, AFM…) available on the nano-characterization platform (PFNC) or in the CEA clean room. Finally, he/she will be involved in the electro-optical characterization of the material, in collaboration with the Cooled Infrared Imaging Laboratory (LIR), which specializes in fine material characterization.