Pore tunability w/o susceptor
Below are a series of TEM micrographs showing a set of membranes produced last week. We RTPed these wafers at 700 (SC 062), 800 (SC 064) and 850 C (SC065) without the susceptor at a ramp rate of 100 C/s.
The trend is increased pore size and porosity with increasing temperature which follows our intuition and previous results. What is interesting is that the 700 C sample has a higher density of smaller pores while the 800 C membrane has a very low density of larger pores. You will also notice that there is a distinct “cornflake texture” in the background. If you look carefully, you will see that the flake size increases and density decreases as RTP temperature increases.
I investigated the 800 C sample further at higher magnifications and found pores that were occluded with a very thin layer of material.
The cornflakes are zones of thinner material surrounded by crystalline features (dark crystals). At higher temperatures > 900 C the texture disappears.