A method of fabricating an infrared detector, a method of controlling the stress in a polycrystalline SiGE layer and an infrared detector device is disclosed. The method of fabricating includes the steps of forming a sacrificial layer on a substrate; patterning said sacrificial layer; establishing a layer consisting essentially of polycrystalline SiGe on said sacrificial layer; depositing an infrared absorber on said polycrystalline SiGe layer; and thereafter removing the sacrificial layer. The method of controlling the stress in a polycrystalline SiGe layer deposited on a substrate is based on varying the deposition pressure. The infrared detector device comprises an active area and an infrared absorber, wherein the active area comprises a polycrystalline SiGe layer, and is suspended above a substrate.