HgCdTe, the material of choice for infrared (IR) detectors, has a low energy of defect formation due to a weak Hg–Te bond. While many defects are common for HgCdTe in general, some of them are specific to the growth method, conditions and substrates used.

Of the many techniques, which are used to characterize the defect structure of HgCdTe, ion milling (IM) is emerging as a unique means to study various defects and complexes. Interstitial mercury atoms, which are released during IM, interact with intrinsic defects and impurities, and by studying electrical properties of HgCdTe before and after IM, one can obtain a pattern of the defect structure of the material. In this paper, we report on the results of applying IM to the study of defects in HgCdTe grown by liquid phase epitaxy (LPE) on CdZnTe substrates. Studied were thick (up to 32 μm) layers for long– (x~0.2) and midwave (x~0.3) IR structures, grown in a closed system LPE machine from Te-rich melts. After the growth the layers were annealed in saturated Hg vapors at 230 ⁰C for 48 hours or at 350⁰C for 5 hours, ion-milled with 500 eV Ar ions with current density 0.2 mA/cm² for 20 min, and left for relaxation of the milling-induced defects at 300 K for 10⁵ min.

The electron concentration in the LPE layers straight after the milling comprised (3‑7)×10¹⁶ cm^‑3. This value is typical for concentration of donor defect complexes formed by IM in high-quality HgCdTe, and is substantially less than that in HgCdTe grown by molecular beam epitaxy, where IM activates specific Te-related defects, yielding very high electron concentration. Upon relaxation, the electron concentration leveled at background doping that differed for layers grown on different CdZnTe substrates and comprised (1–10)×10¹⁴ cm^‑3, which, as a whole, spoke of the high purity of the layers. We discuss the properties of the layers and possible ways, in which the parameters of the CdZnTe substrates affect the electrical properties of the epitaxial material.

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