Au Nanoparticles deposited on tented posts

ByGreg Madejski

Continuing my work from last week, Tucker used the same tenting (NPN, vapor transfer) and incubation procedure (20 nm and 60 nm Au particles) on an oxide substrate with posts (200 nm high). The substrate was dessicated in the 70C oven overnight. No additional platinum or gold coatings were made. The sample was tilted slightly on the SEM stub, so I used a tilt compensation of 10 degrees to keep everything in focus.

Image without tilt compensation.
Image without tilt compensation. The items are blurry in the top portion of the image.
Oxide patterned region with tented membrane over posts. The tented region consists of rings around each post. Some of the rings have an interesting high contrast pattern on them.
Oxide patterned region with tented membrane over posts. The tented region consists of rings around each post. Some of the rings have an interesting high contrast pattern on them.
Freestanding region tented pillars are on the right, and tented regions over the substrate are on the left. Some have high contrast, which is most likely a residue from drying or potentially particles stuck underneath. There are a few small salt crystals (cubes lower left) in the image.
Freestanding region tented pillars are on the right, and tented regions over the substrate are on the left. Some have high contrast, which is most likely a residue from drying or potentially particles stuck underneath. There are a few small salt crystals (cubes lower left) in the image.
60 nm Au aggregates on top of a tented region.
60 nm Au aggregates on top of a tented region.
There are many holes, but no single 60 nm Au particle could fit through any of them.
There are many holes, but no single 60 nm Au particle could fit through any of them.
Small 25 nm particle near hole.
Small 25 nm particle near hole.
Tented pillar region over substrate.
Tented pillar region over substrate.

 

Magnified view of this pillar with large nanoparticles on top of the tent, and smaller ones occupying the holes.
Magnified view of this pillar with large nanoparticles on top of the tent, and smaller ones occupying the holes.

 

Next, we will have to break the nanomembrane tent and see if we can observe particulate on the bottom surface.

Update 6/25/15 – We broke the tent

No metallization yet, just scratched the tweezers across the surface.

NANOPOROUS+AU_broke00

Large scale particulates (60 nm aggregate) are mostly in place)
Large scale particulates (60 nm aggregate) are mostly in place)
Broken post. The tented radius is about 1.5 microns.
Broken post. The tented radius is about 1.5 microns.
Broken area near post, which would have been under tent. Nanoparticles near bottom part of image
Broken area near post, which would have been under tent. Nanoparticles near bottom part of image
Distance to particles
Distance to particles

NANOPOROUS+AU_broke10

Particles are about the right size.
Particles are about the right size.

 

I’m going to metallize with platinum to get clearer images.

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