Abstract: The manufacture of monolithic HgCdTe detectors and Si circuitry in an IR focal plane array is achieved by forming a protective layer of SiO.sub.2 or SiN.sub.x on a silicon wafer containing silicon circuits, etching steep-wall recesses into the wafer, selectively depositing epitaxial single-crystal layers of GaAs, CdTe, and HgCdTe in the recesses fabricating HgCdTe IR arrays, and depositing appropriate insulating and conductive interconnection patterns to interconnect the Si devices with one another and the HgCdTe devices with the Si devices. Little or no GaAs, CdTe, and HgCdTe grows on the SiO.sub.2 or SiN.sub.x outside the recesses. Since material grown outside the recess is polycrystalline, it is easily chemomechanically removed.

Abstract: The manufacture of monolithic HgCdTe detectors and Si circuitry in an IR focal plane array is achieved by forming a protective layer of SiO.sub.2 or SiN.sub.x on a silicon wafer containing silicon circuits, etching steep-wall recesses into the wafer, selectively depositing epitaxial single-crystal layers of GaAs, CdTe, and HgCdTe in the recesses fabricating HgCdTe IR arrays, and depositing appropriate insulating and conductive interconnection patterns to interconnect the Si devices with one another and the HgCdTe devices with the Si devices. Little or no GaAs, CdTe, and HgCdTe grows on the SiO.sub.2 or SiN.sub.x outside the recesses. Since material grown outside the recess is polycrystalline, it is easily chemomechanically removed.