I did a small experiment to demonstrate that a carbonized membrane would be stable in a harsh alkaline solution, such as KOH. I soaked a carbonized membrane and untreated membrane in %5 KOH at 40 C for an hour in an oven. As you can see, the carbonized membrane is still in-tact and the untreated…
Inspired by some recent literature that I have been reading, I decided to add an argon bombardment step after the amorphous silicon deposition step by applying a 50 W substrate bias. The idea is that point defects on the surface of the a-Si will become seeds for crystallization and thus lower the crystallization temperature and…
Recently, I have been trying to pass 5 nm, 10 nm, and 15 nm gold through untreated, carbonized, and ozone/carbonized membranes. These experiments were done in the pressure cell with fresh samples. I used a 1:1 dilution of Au stock and DI water. To wet the membrane I placed a 40 uL drop of water…
Last week, I used a 6-inch thermocouple wafer to profile the temperature uniformity (outside the susceptor) in the RTP. I measured four points: center, front, back, and center-right (positions relative to the RTP door e.g. front means closer to the door). The center-right position was chosen to verify side-to-side uniformity of the lamps. Below is…
Today I tried to pass 5 nm gold through three different membranes with similar cut-offs but distinct mean diameters and porosities. All the samples I used were ozoned yesterday and tested for water permeability. Based on the absorbance measurements, it seems that the 5 nm Au passes through 582 and 558 but not the carbonized…
I tested four membranes with different porosities today, including one that had been carbonized. Here are the pore size distributions with TEM micrographs. I ozone treated all the samples prior to running the experiments, including the carbonized sc 582. I expected some of the carbon ring to oxidize, which TEM confirms: It would appear that…
I did two tests using water straight out of the Barnstead and with water from the cleanroom in Hopeman. I was able to maintain high permeability using the same membrane for at least three successive trials with both. It looks like the culprit is the Nalgene container used to store the water. For any sensitive…
I’ve become increasing suspicious of the membrane clogging during the hydraulic permeability experiments. I ran an experiment where I took three fresh samples (sc 582) and pushed water through for 5, 10, and 20 minutes. Ideally, the permeability would be the same for all three time points. However, I observed a decrease at each increasing…
Looking back at production over the last year, I noticed that our porosity has dropped considerably. Now that we have a good handle on controlling pinhole density, it is time to focus on controlling morphology again. Below are two examples of a 15 nm and 30 nm pnc-Si film produced this month and one year…
In a first attempt to reduce the electrostatic drag that might be slowing water transport, I ran an experiment with 1x PBS. The membranes were first ozone treated and then assembled into the SepCon inserts. From these first trials, it appears that PBS does pass through more quickly than DI water.