Low-temperature annealing of (Hg,Cd)Te |
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Authors: | D Chandra H F Schaake M A Kinch |
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Affiliation: | (1) DRS Infrared Technologies, L.P., 75374 Dallas, TX |
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Abstract: | Many methods for the employment of (Hg,Cd)Te alloys employ anneals at temperatures <300°C to convert the p type left over
from the growth process or to adjust the concentration of the native acceptors. An investigation of the kinetics of this annealing
process has been performed as functions of (1) vacancy concentration; (2) composition, or the CdTe mole fraction in the alloy;
and (3) temperature. If these anneals are carried out under mercury-saturated conditions, the tellurium precipitates in the
material, which result either from the growth process or from specific thermal histories, are annihilated by in-diffusing
mercury, which results in a significant multiplication of dislocations. This interface, delineated by defect etching, has
been employed to investigate the kinetics of the annealing process. These results will be unaffected by the uncertainties
introduced in determining this interface by electrical measurements, which arise from incomplete ionizations of the metal
vacancies at 77 K for Hg1−xCdxTe with CdTe mole fractions exceeding ∼0.26. The annealing rate appears to be strongly dependent on both the temperature and
composition of the alloy, decreasing with increasing CdTe mole fraction, within 0.15 and 0.5, with the behavior resembling
a composition-dependent, activated-diffusion process. The depth of the interface appears to vary inversely as the root of
the metal-vacancy concentration. |
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Keywords: | HgCdTe Te precipitates annealing |
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