TEM pixel:nm conversion, permeability numbers
Here are the conversion ratios for the URMC TEM images (so we’re all using the same standard):
30kx – 0.39 px/nm
50kx – 0.67 px/nm
150kx – 2.2 px/nm
300kx – 4.5 px/nm
These numbers should be used for wafers 187, 189, and > 310.
Unlike the RC TEM conversions, these numbers seem to be consistent between the different mags i.e. 150kx ratio is ~3x 50x ratio, 300kx is ~2x 150kx ratio.
Here are the RC TEM coversion:
25 kx – 1.01 px/nm
35kx – 1.07 px/nm
50kx – 1.93 px/nm
75kx – 3.34 px/nm *
100kx – 2.92 px/nm *
150kx – 5.14 px/nm
* It seems that these two are out of order, but this is what Brian’s camera is set to…
I also did a quick calculation to follow up Philippe’s comment about the strong dependence (fourth power) of pore radius in the permeability equation. Using Jim’s permeability script, I found that a -5% change in pore radius results in a decrease of permeability from 700 uL/cm^2-min-PSI to 628 uL/cm^2-min-PSI. A +5% change yielded a permeability of 885 uL/cm^2-min-PSI.
The take-home is that even if we’re overestimating our pore size by 5%, our observed 310 uL/cm^2-min-PSI from wafer 310 is still %50 lower than theory.
Dave you just saved me a bunch of trouble. Thanks! Can you update this post with the conversions that should be used for RC TEM and a guide to help us know which system was used for which wafers? Wafer numbers or a transition date will probably work.
We should still plan on buying some nanoparticles or some other reference material. We could throw some on a membrane and take an average of 10 or so to confirm the scale bars…