Electrochemical etching of AlGaN for the realization of thin-film devices
Journal article, 2019

Heterogeneously integrated AlGaN epitaxial layers will be essential for future optical and electrical devices like thin-film flip-chip ultraviolet (UV) light-emitting diodes, UV vertical-cavity surface-emitting lasers, and high-electron mobility transistors on efficient heat sinks. Such AlGaN-membranes will also enable flexible and micromechanical devices. However, to develop a method to separate the AlGaN-device membranes from the substrate has proven to be challenging, in particular, for high-quality device materials, which require the use of a lattice-matched AlGaN sacrificial layer. We demonstrate an electrochemical etching method by which it is possible to achieve complete lateral etching of an AlGaN sacrificial layer with up to 50% Al-content. The influence of etching voltage and the Al-content of the sacrificial layer on the etching process is investigated. The etched N-polar surface shows the same macroscopic topography as that of the as-grown epitaxial structure, and the root-mean square roughness is 3.5 nm for 1 µm x 1 µm scan areas. Separated device layers have a well-defined thickness and smooth etched surfaces. Transferred multi-quantum-well structures were fabricated and investigated by time-resolved photoluminescence measurements. The quantum wells showed no sign of degradation caused by the thin-film process.




Electrochemical etching


Michael Alexander Bergmann

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Johannes Enslin

Technische Universität Berlin

Rinat Yapparov

Royal Institute of Technology (KTH)

Filip Hjort

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Björn Wickman

Chalmers, Physics, Chemical Physics

Saulius Marcinkevičius

Royal Institute of Technology (KTH)

Tim Wernicke

Technische Universität Berlin

Michael Kneissl

Technische Universität Berlin

Åsa Haglund

Chalmers, Microtechnology and Nanoscience (MC2), Photonics

Applied Physics Letters

0003-6951 (ISSN) 1077-3118 (eISSN)

Vol. 115 18 182103-

Areas of Advance

Nanoscience and Nanotechnology (2010-2017)

Subject Categories

Other Physics Topics

Nano Technology

Condensed Matter Physics


Chalmers Materials Analysis Laboratory

Nanofabrication Laboratory



More information

Latest update