Abstract:
Using the adiabatic approximation, the capture coefficient of conduction band electrons on $A_2^{-2}$ mercury vacancy levels in HgCdTe semiconductors with a band gap of more than $\sim$100 meV (with a Cd fraction in the solution $x >$ 0.2) was estimated. It is shown that electron capture on the vacancies is significantly suppressed with an increase in the cadmium content. For example, the low-temperature capture coefficient decreases from $\sim$10$^{-8}$ cm$^3$$\cdot$ c$^{-1}$ at $x$ = 0.21 to $\sim$10$^{-12}$ cm$^3$$\cdot$ c$^{-1}$ at $x$ = 0.25. The low rate of electron capture in wide-band HgCdTe layers is mainly due to the significant distance of mercury vacancy levels from the bottom of the conduction band, as well as the moderately weak electron-phonon coupling of electrons localized in vacancies (Huang-Rhys factor $S <$ 0.5).
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