Ion milling was used to establish the minimum donor doping level N md required for obtaining n-regions with reproducible electron concentration in HgCdTe-based LWIR and MWIR device structures fabricated with ion treatment. The experiments were performed on n-type films grown by molecular beam epitaxy, un-doped and in situ doped with indium with the concentration N In = 5 × 10 14 -10 17 cm −3 . A study of the electrical properties of the milled films showed that N md comprised ∼2 × 10 15 cm −3 for the LWIR and ∼5 × 10 15 cm −3 for the MWIR films. In the films with N In exceeding these critical values, the electron concentration after the milling strictly followed the doping. A need for consideration of the disintegration of the milling-induced defects is also shown.

An ion milling-assisted study of defect structure of HgCdTe films grown by molecular beam epitaxy on Si substrates was performed. The films appeared to contain initially neutral Te-related defects with concentration of 10 17 cm −3 , typical of HgCdTe. The concentration of residual donors was found to be quite low ((3-8) × 10 14 cm −3 ). Specific to HgCdTe/Si technology appeared to be a considerable number of stacking faults, which affected the carrier mobility in n-type material. These defects can be annealed in He atmosphere at 230 • C, and after ion milling the electrical parameters of n-type HgCdTe/Si films approach those of high-quality bulk crystals.

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The Hall effect and photoluminescence measurements combined with annealing and/or ion milling were used to study the electrical and optical properties of HgCdTe films grown by molecular-beam epitaxy on GaAs substrates with ZnTe and CdTe buffer layers. Unintentional donor doping, likely from the substrate, which resulted in residual donor concentration of the order of 1015 cm−3, was observed in the films. Also, acceptor states, possibly related to structural defects, were observed.