I’m not sure how many people in the current group have read all the papers that we have published, but a critical one was a JACS paper from Shigeru Amemiya where he used his Scanning ElectroChemical Microscopy (SECM) to probe the permeability of our membranes at the micron scale. In the supplement to this paper,…
Here’s a cropped image from a recent TEM pic that Brian McIntyre took of our material for SiMPore (15 nm thickness, not sure what wafer). This particular feature caught my eye because the crystal is perfectly aligned so we are looking at individual atomic columns of Si, instead of the typical crystal planes. These happen…
I did some imaging on the URinc TEM today and took the nice image below from wafer SC021. I wanted to see the correlation between highly diffracting (dark) crystals in our standard lower resolution TEM and the lattice fringes observed at high-res. In the image, the very strong <111> lattice fringe area to the upper…
As many of you know, we have been having a lot of trouble with the new etch cell and have not been able to produce high quality membranes. Yesterday, we discovered that the stainless steel used to fabricate the new cell is different than that of the original cell. Here are the EDAX spectra: Old…
I think some of us have been confusing each other in our discussions of the dependence of flow rate on pore radius. Jim thinks in terms of a single pore, and I agree that there is an r^4 dependence. Therefore, if you double the pore radius, flow would increase 16X with everything else being equal….
Dave and I tested 8 wafers (187, 189, 310, 316, 318, 325, 327, 329) from the last 3 runs and traces of copper can be found within all the wells. However, the amount and position of this contamination varies greatly, with the most particles being located near the top of the well, away from the…
This is probably not of general interest, but for the sake of full disclosure, I have spent considerable time working with our wafer supplier (Virginia Seiconductor) to resolve some issues regarding the surface quality of their wafers. It would have been much more productive to simply switch suppliers, but unfortunately, they are the only place…
After the w310 series being beautiful (few pinholes, reasonable strength, high yield), we have retreated somewhat with a return of the copper-related piholes. Here is an SEM image and EDX scan from the well wall: Here is a pic of a pinhole on the membrane with a telltale copper silicide particle attached to the edge:…
I think the consistently low flow rates are a real bottleneck for all our fluid based experiments and must be overcome. On the production side, we are really pushing the limits of our capabilities to produce the current membrane geometry, which I consider to be crazy big at 0.1 x 2 mm!! Considering the 15…
There is strong evidence that the recent pinhole breakout is due to copper contamination in our process. I have attached two image – An SEM showing a cuprous creature eating one of our membranes and an EDX (Energy Dispersive X-ray?) spectra identifying it as a copper-rich silicide. This would also explain Dave’s TEM image of…