Donor-Acceptor Pairs Recombination as the Origin of the Emission Shift In InGaN/GaN Scintillator Heterostructures Doped with Zn

We report luminescence decay characteristics of the InGaN/GaN scintillator heterostructures doped with Zn. Unusually large shifting of luminescence band caused by Zn acceptors incorporated in InGaN is observed both in time-resolved and excitation-dependent spectra. Origins of the shifts are discussed, and model based on donor-acceptor pair recombination is introduced. The results imply a shrinkage of donor Bohr radius compared to the bulk material caused by quantum confinement effect. The slow decay of Zn band points out to the necessity of Zn impurity elimination in applications requiring fast timing characteristics of a scintillator.