Berlin 2008 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
HL: Fachverband Halbleiterphysik
HL 49: ZnO: Optical properties
HL 49.9: Vortrag
Donnerstag, 28. Februar 2008, 12:45–13:00, ER 164
Stacking fault-related 3.31eV luminescence in zinc oxide — •M. Schirra1, R. Schneider1, A. Reiser1, G.M. Prinz1, M. Feneberg1, J. Biskupek2, U. Kaiser2, C.E. Krill3, R. Sauer1, and K. Thonke1 — 1Institut für Halbleiterphysik, Universität Ulm, D-89069 Ulm — 2Materialwissenschaftliche Elektronenmikrokopie, Universität Ulm, D-89069 Ulm — 3Institut für Mikro- und Nanomaterialien, Universität Ulm, D-89069 Ulm
Epitaxial layers, bulk material, and nanostructures of ZnO often exhibit a characteristic luminescence band at ≈3.31eV. The nature and origin of this band has been the subject of some debate, frequently being interpreted in terms of acceptor-related recombination taken as confirmation of successful p-type doping. Our epitaxial ZnO layers, grown nominally undoped on a-plane sapphire substrates, also show the 3.31eV band together with dominant near-band edge emission. A combination of spatially resolved cathodoluminescence (CL) and transmission electron microscopy (TEM) studies performed on the same samples finds that the 3.31eV band appears along distinct lines, which we identify as being related to basal plane stacking faults. Temperature-dependent CL measurements reveal that the 3.31eV band is a free-to-bound (e,A0) transition, involving an acceptor state localized at the stacking fault. The acceptor ionization energy is 130meV. Some samples show an additional line ≈13meV below the 3.31eV band. Its properties are consistent with a donor-acceptor-pair transition. The average pair distance is only 4nm. Possible implications of these new results with regard to p-type doping of ZnO are discussed.