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HL: Fachverband Halbleiterphysik
HL 8: Nitrides: Devices
HL 8.8: Vortrag
Montag, 16. März 2020, 11:15–11:30, POT 51
AlGaN-based UVC-LEDs on AlN/sapphire templates with low threading dislocation density — •Daniel Hauer Vidal1, Norman Susilo1, Arne Knauer2, Sylvia Hagedorn2, Johannes Enslin1, Tim Wernicke1, Markus Weyers2, and Michael Kneissl1 — 1Technische Universität Berlin, Berlin, Deutschland — 2Ferdinand-Braun-Institut, Berlin, Deutschland
AlGaN-based ultraviolet light emitting diodes (UV LEDs) near 265 nm have applications for the desinfection of water, surfaces and medical equipment. However, most devices are grown on AlN/sapphire templates, which have a high threading dislocation density (TDD). One method to reduce the TDD to around 2 × 109 cm−2 are epitaxially laterally overgrown (ELO) AlN/sapphire-templates. They are produced by overgrowing a sapphire template with 0.8 µm of AlN. This layer is then patterned with 1.5 µm thick ridges and subsequently overgrown with several µm of AlN until coalescence. Recently a new approach was developed using high temperature annealing (HTA). In this method a AlN/sapphire template is face to face annealed at temperatures above 1500∘C. The annealing step leads to a restructuration of the AlN layer, which produces templates with TDDs at around 1 × 109 cm−2. Another method to reduce the TDD within the active region is to manipuilate the growth mode using different susbtrat off-cut angles. In this study we compare UVC-LEDS grown by metalorganic vapor phase epitaxy on HTA, ELO AlN/sapphire and their combination HTA-ELO. Finally UVC-LEDs are realised on HTA-ELO showing an emission power of 47 mW at 350 mA and 265 nm.