Effects of disorder on the optical properties of deep UV quantum well emitters as assessed by photonic atom probe

The Photonic Atom Probe, a technique allowing the simultaneous, in situ acquisition of photoluminescence within a tomographic atom probe, is applied to the study of AlGaN quantum wells within deep-UV (DUV) separate confinement heterostructures. The analyzed sample exhibits a high degree of compositional and morphological disorder, translating into spatial inhomogeneities and a significant dispersion of photoluminescence emission energy. We show how the proposed in situ correlative microscopy approach can explain different optical emission features in these structures, particularly the distinction between the optical signatures of non-defective quantum well (QW) and QWs located within defective regions. The results, including time-resolved photoluminescence, are interpreted through eight-band k.p calculations, which take as an input to the statistical properties extracted from the atom probe tomography composition maps. This links DUV emission heterogeneity to nanoscale disorder within the same analyzed volume, providing insight relevant to improving multi-QW structures.