Dresden 2017 – wissenschaftliches Programm
HL 25.16: Poster
Montag, 20. März 2017, 15:00–19:00, P2-OG2
Determination of threading dislocation density of AlN on sapphire substrates by X-ray diffraction — •Daniel Pacak1, Johannes Enslin1, Tim Wernicke1, Sylvia Hagedorn2, Arne Knauer2, Carsten Hartmann3, Heike Oppermann3, Markus Weyers2, and Michael Kneissl1,2 — 1Technische Universität Berlin, Institute of Solid State Physics — 2Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik — 3Leibniz-Institut für Kristallzüchtung, Berlin
AlN on sapphire substrates with low threading dislocation density (TDD) is essential for the growth of efficient UV light emitting diodes. The TDDs of a series of AlN layers on sapphire with different dislocation densities, ranging from 1·109cm−2 to 2·1010cm−2 were determined by X-ray diffraction (XRD) by measuring the FWHM of ω-scans for different reflections. For this, we first separated the broadening of the XRD peaks due to finite coherent length and wafer curvature from the broadening by tilt and twist. Then the tilt and twist contributions were determined by two different approaches. One method was based on obtaining the tilt value by measuring a reflection in asymmetric geometry and calculating the corresponding twist value. In a second approach the tilt and twist components were determined by extrapolating the FWHM against the χ-angle. From these tilt and twist values we calculated the TDDs for correlated and randomly distributed dislocations, based on the models of Chierchia et al. and Dunn & Kogh. Finally we compared the TDD obtained by XRD with the results from defect selective etching.