The usefulness of scattering-type near-field optical microscopy for mapping the material and doping in microelectronic devices at nanoscale resolution is demonstrated. Both amplitude and phase of infrared (λ = 10.7 μm) laser light scattered by a metallised, vibrating AFM tip scanned a few nanometers above the sample are detected and transformed into images showing contrast of materials, as well as of doping concentration. Cross-sections through layers as thin as 20 nm have been clearly imaged.