Electron radiation damage and annealing of Hg1−xCdxTe at low temperatures

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Abstract
Samples of Hg1−x Cd x Te with x=0.22 and x=0.31 have been irradiated with dosages of up to 4.7×1015 electrons/cm2 of 2.5‐MeV electrons. During the irradiation the sample temperature was below 25 °K. The samples were initally p type, i.e., at 77 °K the hole carrier concentrations were in the range (2.5–4.3)×1016cm−3. After irradiation all samples were found to be n type. A dose of 4.7×1015 electrons/cm2 yielded an electron carrier concentration of 1.5×1017 cm−3 at 8 °K and an electrical conductivity σ four orders of magnitude larger than the unirradiated σ at 8 °K. The electron Hall mobility for low dosages and small measured electron concentrations is very low (500–2500 cm2/V sec). As the dosage is increased, the mobility rises rapidly and then saturates. Postirradiation annealing results in almost complete restoration of the transport properties. Much of the annealing occurs between 50 and 75 °K. The luminescence and photovoltaic response (at 8 °K) of the x=0.31 samples were measured before irradiation, after irradiation, and at several stages of the annealing. The irradiation shifts the luminescence and the photovoltaic response cutoffs to lower energies. Most of this change in optical properties anneals out between 100 and 250 °K.