Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 51: Poster IV

HL 51.37: Poster

Donnerstag, 28. Februar 2008, 16:30–19:00, Poster D

Structural properties of ZnO Nanorods before and after Ga-Implantation in a Focused-Ion-Beam-System — •Michael Dürrschnabel¹, Daniel Weissenberger¹, Dagmar Gerthsen¹, Anton Reiser², Günther Prinz², Martin Feneberg², Klaus Thonke², and Rolf Sauer² — ¹Laboratorium für Elektronenmikroskopie, Universität Karlsruhe, D-76128 Karlsruhe, Germany — ²Institut für Halbleiterphysik, Universität Ulm, D-89081 Ulm, Germany

The structural properties of ZnO nanorods grown by the vapor-liquid-solid technique on sapphire were studied by transmission electron microscopy. Implantations were carried out in a focused-ion-beam system with 30 keV Ga⁺ ions and doses D from 10¹¹ to 10¹⁶ cm⁻². The nanorods are almost free of defects before implantation. Small defects with extensions below 9 nm and a density of 5x10¹⁵ cm⁻³ are found for 10¹¹ ≤ D ≤ 10¹² cm⁻². At D = 10¹⁴ cm⁻², dislocation loops with diameters up to 20 nm and a concentration of 1.8x10¹⁷ cm⁻³ are formed. The dislocation loops bind stacking faults which consist of inserted or missing (0002) planes oriented perpendicular to the [0001] nanorod axis. At D = 10¹⁶ cm⁻², the planar defects agglomerate and form three-dimensionally defective regions. Energy dispersive X-ray analysis yield a Ga-concentration of about 1 % for D = 10¹⁶ cm⁻² leading to a resistivity decrease from 0.04 Ωcm before implantation to 0.003 Ωcm after implantation despite the high defect density which strongly lowers the mobility.