Fabrication and chemical lift-off of sub-micron scale III-nitride LED structures

Abstract

Nanoscale light-emitting diodes (nanoLEDs, diameter < 1 µm), with active and sacrificial multi-quantum well (MQW) layers epitaxially grown via metal organic chemical vapor deposition, were fabricated and released into solution using a combination of colloidal lithography and photoelectrochemical (PEC) etching of the sacrificial MQW layer. PEC etch conditions were optimized to minimize undercut roughness, and thus limit damage to the active MQW layer. NanoLED emission was blue-shifted ∼10 nm from as-grown (unpatterned) LED material, hinting at strain relaxation in the active InGaN MQW layer. X-ray diffraction also suggests that strain relaxation occurs upon nanopatterning, which likely results in less quantum confined Stark effect. Internal quantum efficiency of the lifted nanoLEDs was estimated at 29% by comparing photoluminescence at 292K and 14K. This work suggests that colloidal lithography, combined with chemical release, could be a viable route to produce solution-processable, high-efficiency nanoscale light emitters.

ICB Affiliated Authors

Authors
Lesley Chan, Therese Karmstrand, Aaron Chan, Pavel Shapturenka, David Hwang, Tal Margalith, Steven P. DenBaars, and Michael J. Gordon
Date
Type
Peer-Reviewed Article
Journal
OSA Optics Express
Volume
28
Number
23
Pages
35038-35046