The ability of the nuclear microprobe with a 2 μm focused beam of MeV He+ions to analyze the active region of individual Hg1−xCdxTe metal–semiconductor–metal (MSM) detectors has been demonstrated. Details of the channeling of Hg1−xCdxTe by Rutherford backscattering spectrometry and the incidence of defects imaged by channeling contrast microscopy were correlated with the performance of devices in a number of arrays. A series of linear growth defects was identified in the active region of some devices using channeling contrast microscopy. The channeling spectra that were extracted from these defective regions have shown a higher value of χmin=24% (the ratio of backscattered particle yield with the crystal 〈100〉 axis aligned with the beam to the yield for a random alignment) than the surrounding crystal χmin=9%–15%. The presence of these linear defects was linked to a degradation in the performance of the corresponding devices in an array. MSM detectors fabricated on Hg1−xCdxTe/GaAs/Si were lower in breakdown voltage than equivalent devices on Hg1−xCdxTe/GaAs. This trend corresponded to a higher value of χminfor the Hg1−xCdxTe on GaAs/Si than with the epitaxial layer grown on GaAs.