From: Correlation between Al grain size, grain boundary grooves and local variations in oxide barrier thickness of Al/AlOx/Al tunnel junctions by transmission electron microscopy
Substrate
\(\hbox {Al}_{2}\hbox {O}_{3}\)
Si
\(\hbox {Si}_{3}\hbox {N}_{4}\)
\(\hbox {SiO}_{2}\)
\(\hbox {SiO}_{2}\) (cold)
\(\langle d \rangle \) (nm)
92 ± 8
78 ± 8
98 ± 8
85 ± 9
62 ± 4
\(\sigma _d\) (nm)
46 ± 10
40 ± 10
57 ± 11
48 ± 12
34 ± 5