Clarification of difference for transition between photoluminescence and cathode-luminescence based on GaMnN

Abstract

GaN:Mn epilayers were grown on Al2O3 substrate uisng molecular beam epitaxy (MBE) and were subsequently implanted with Mn+ ions (1% and 10%). Photoluminescence (PL) with 1% of Mn showed that optical transitions related to Mn revealed the donor-Mn pair (D, Mn) at 2.5eV and the electron-Mn pair (e, Mn) around 3.1eV, and yellow luminescence (YL) around 2.20–2.25eV. Photoluminescence (PL) with 10% of Mn showed the same but enhanced optical transitions as above. However, the new transitions around 1.65eV for the sample with 10% which did not appeared with Mn of 1% were very weakly produced. The results of cathode-luminescence (CL) with 10% of Mn showed transitions related to Mn in PL together with new transitions around 1.72eV. However, the new transitions around 1.72eV for the sample with 10% according to high accelerating voltage were very remarkably activated in contrast with PL transitions which appeared were very weakly produced in samples with Mn of 10%. Transitions around 1.72eV in CL correspond to though around 1.65eV in PL. This result means that deep donor (probably, VN) is detected with increasing accelerating voltage and Mn–VN complex is formed. This is supported by strong electron beam sensitivity of the IR emission bands. It is well known that heavy Mn doping (>∼1019Cm−3) leads to a downshift of the Fermi level and promotes the formation of defect complexes of Mn–VN. In our case, Mn doping concentration is >∼1021Cm−3. Therefore, it is conjectured that the CL transition around 1.72eV corresponds to Mn–VN complex.