Fabrication, self-assembly, and properties of ultrathin AlN/GaN porous crystalline nanomembranes: tubes, spirals, and curved sheets.
Ultrathin AlN/GaN crystalline porous freestanding nanomembranes are fabricated on Si(111) by selective silicon etching, and self-assembled into various geometries such as tubes, spirals, and curved sheets. Nanopores with sizes from several to tens of nanometers are produced in nanomembranes of 20-35 nm nominal thickness, caused by the island growth of AlN on Si(111). No crystal-orientation dependence is observed while releasing the AlN/GaN nanomembranes from the Si substrate indicating that the driving stress mainly originates from the zipping effect among islands during growth. Competition between different relaxation mechanisms is experimentally revealed for different nanomembrane geometries and well-described by numerical calculations. The cathodoluminescence emission from GaN nanomembranes reveals a weak peak close to the GaN bandgap, which is dramatically enhanced by electron irradiation.
Mei
Yongfeng
Y
Institute for Integrative Nanosciences, IFW Dresden, Helmholtzstrasse 20, D-01069 Dresden, Germany.
Thurmer
Dominic J
DJ
Deneke
Christoph
C
Kiravittaya
Suwit
S
Chen
Yuan-Fu
YF
Dadgar
Armin
A
Bertram
Frank
F
Bastek
Barbara
B
Krost
Alois
A
Christen
Jürgen
J
Reindl
Thomas
T
Stoffel
Mathieu
M
Coric
Emica
E
Schmidt
Oliver G
OG