It was noted that, during the growth of InGaN/GaN multiple quantum-well structures, a new defect (the so-called V-defect) nucleated at threading dislocations in one of the first quantum wells in a multiple quantum-well stack. This defect was common to almost all InGaN multiple quantum-well heterostructures. The nature of the V-defect was evaluated here by applying transmission electron microscopy, scanning transmission electron microscopy, and low-temperature cathodoluminescence techniques to a series of Ga0.80In0.20N/GaN multiple quantum-well samples. The structure of the V-defect comprised buried side-wall quantum wells, on the {10•1} planes, and an open hexagonal inverted pyramid which was defined by the six {10•1} planes. This defect therefore appeared as an open 'V' when seen in cross section. The formation of the V-defect was controlled kinetically by reduced Ga incorporation at the pyramid walls; the {10•1} planes. The V-defect was related to localized excitonic recombination centers that gave rise to a long-wavelength shoulder in photoluminescence and cathodoluminescence spectra.

X.H.Wu, C.R.Elsass, A.Abare, M.Mack, S.Keller, P.M.Petroff, P.M.DenBaars, J.S.Specka, S.J.Rosner: Applied Physics Letters, 1998, 72[6], 692-4