Stability of the positively charged manganese centre in GaAs heterostructures examined theoretically by the effective mass approximation calculation near the Γ critical point

This paper describes an n—i—p—i—n model heterostructure with a manganese (Mn)-doped p-type base region to check the stability of a positively charged manganese A+Mn centre with two holes weakly bound by a negatively charged 3d5(Mn) core of a local spin S = 5/2 in the framework of the effective mass approximation near the Γ critical point (k ∼ 0). By including the carrier screening effect, the ground state energy and the binding energy of the second hole in the positively charged centre A+Mn are calculated within a hole concentration range from 1 × 1016 cm−3 to 1 × 1017 cm−3, which is achievable by biasing the structure under photo-excitation. For comparison, the ground-state energy of a single hole in the neutral A0Mn centre is calculated in the same concentration range. It turns out that the binding energy of the second hole in the A+Mn centre varies from 9.27 meV to 4.57 meV. We propose that the presence of the A+Mn centre can be examined by measuring the photoluminescence from recombination of electrons in the conduction band with the bound holes in the A+Mn centre since a high frequency dielectric constant of in∞ = 10.66 can be safely adopted in this case. The novel feature of the ability to tune the impurity level of the A+Mn centre makes it attractive for optically and electrically manipulating local magnetic spins in semiconductors. (general)