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Improving AlN Crystal Quality and Strain Management on Nanopatterned Sapphire Substrates by High‐Temperature Annealing for UVC Light‐Emitting Diodes
Author(s) -
Hagedorn Sylvia,
Walde Sebastian,
Susilo Norman,
Netzel Carsten,
Tillner Nadine,
Unger Ralph-Stephan,
Manley Phillip,
Ziffer Eviathar,
Wernicke Tim,
Becker Christiane,
Lugauer Hans-Jürgen,
Kneissl Michael,
Weyers Markus
Publication year - 2020
Publication title -
physica status solidi (a)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.532
H-Index - 104
eISSN - 1862-6319
pISSN - 1862-6300
DOI - 10.1002/pssa.201900796
Subject(s) - sapphire , materials science , optoelectronics , light emitting diode , annealing (glass) , diode , epitaxy , heterojunction , wafer , nucleation , dislocation , layer (electronics) , nanotechnology , optics , composite material , laser , chemistry , physics , organic chemistry
Herein, AlN growth by metalorganic vapor‐phase epitaxy on hole‐type nanopatterned sapphire substrates is investigated. Cracking occurs for an unexpectedly thin‐layer thickness, which is associated to altered nucleation conditions caused by the sapphire pattern. To overcome the obstacle of cracking and at the same time to decrease the threading dislocation density by an order of magnitude, high‐temperature annealing (HTA) of a 300 nm‐thick AlN starting layer is successfully introduced. By this method, 800 nm‐thick, fully coalesced and crack‐free AlN is grown on 2 in. nanopatterned sapphire wafers. The usability of such templates as basis for UVC light‐emitting diodes (LEDs) is furthermore proved by subsequent growth of an UVC‐LED heterostructure with single peak emission at 265 nm. Prerequisites for the enhancement of the light extraction efficiency by hole‐type nanopatterned sapphire substrates are discussed.