Hydrogen passivation and multiple hydrogen–Hg vacancy complex impurities (nH–VHg, n = 1,2,3,4) in Hg0.75Cd0.25Te

Abstract

Using first-principles method within the framework of the density functional theory, we study the formation energies and the binding energies of multiple hydrogen–mercury vacancy complex impurities (nH–VHg, n = 1,2,3,4) in Hg0.75Cd0.25Te. We find that, when mercury vacancies exist in Hg0.75Cd0.25Te, the formation of the complex impurity between H and VHg (1H–VHg) is easy and its binding energy is up to 0.56 eV. In this case, the deep acceptor level of mercury vacancy is passivated. As the hydrogen concentration increases, we find that the complex impurity between VHg and two hydrogen atoms (2H–VHg) is more stable than 1H–VHg. This complex passivates both the two acceptor levels introduced by mercury vacancy and neutralizes the p-type dopant characteristics of VHg in Hg0.75Cd0.25Te. Moreover, we find that the complex impurities formed by one VHg and three or four H atoms (3H–VHg, 4H–VHg) are still stable in Hg0.75Cd0.25Te, changing the VHg doped p-type Hg0.75Cd0.25Te to n-type material.