Photoluminescence in Mn-implanted GaAs—An explanation on the ∼1.40-eV emission

Abstract

The emission properties of Mn‐implanted layers in GaAs are investigated with respect to changes in excitation intensity, temperature, substrate, and encapsulation. The substrates used were n‐type conducting and Cr‐doped semi‐insulating crystals. The depth‐dependent measurements of the Mn emission show an increase of the diffusion coefficient with dose for Si₃N₄ encapsulated samples, whereas a suppression of Mn diffusion is observed for SiO₂ encapsulated samples. A large energy shift from ∼1.36 to 1.41 eV is observed for Mn emission at 4.2 °K at various excitation intensities. The energy shift increases with the concentration of compensating donors in the n‐type substrate material. The excitation‐dependent emissions are due to the donor‐acceptor pair type transitions in the normal and the random‐impurity‐potential‐disturbed energy states of the bands. Another emission becomes dominant at T≳∼30 °K following the quenching of the donor‐acceptor pair type transitions with an increase of the temperature. An activation energy 95±15 meV is obtained from the temperature quenching of the emission intensity and the energy shift is observed to follow the band‐gap variation. The possible radiative mechanisms are discussed.