Electron-irradiated silicon photoconductors have been fabricated and characterised for focal-plane array applications. The photoresponse has a peak at 4 μm where Dλ* values of 2×1010 cm Hz½W−1 have been measured at 80 K. These characteristics are maintained to 100 K before thermal generation becomes significant. The devices are stable in processing and storage up to at least 100°C. Since no deep-level chemical dopants are involved, dedicated silicon processing facilities are not required