Getting the Software Down

Last Thursday on my trip to Tulsa I was able to begin designing a template to be used with the e-beam hardware.  Unfortunately the e-beam and the SEM are not yet "talking" to each other, but the software itself is still operational.  Therefore, I was able to read the manual and make some decisions that will make using the e-beam much easier, as soon as it is operational.  One concern that the professor I've been working with at TU is that because the e-beam is different than the one they used previously (with the group before me) is that the counts/dose ( the energy delivered to the sample per specified area, line or spot) will be different.  This means that we can't just use the settings that were used prior and expect the same results right off the bat.
In order to determine the correct dose, I made a template the features several lines which I made different colors on the program.  Then I can make each differently colored line a different dosage and examine the results to determine which lines didn't go deep enough, which ones gave poor resolution and which give the best results.  There are still other optimization problems that go along with the system, such as the SEM optimization itself (stigmators, apertures, etc.) but I have quite a bit of practice with this and there is a very skilled technician available to assist if needed.
If the e-beam and software are not communicating by Thursday this week then I will forego a trip there this week as I feel that there is not much I can really do until that is completed, at least not that would warrant my driving there.
On the other side of the project (terraces) I am also moving forward.  I have made 5 200 nm sphere samples and today or tomorrow I am working with a research scientist here at OU to determine if there is anyway to clean the surfactant of the surface of the sphere layers using different solvents.  We will immerse the samples in 4 different solvents and keep one a control in order to determine what effect they have on their cleaning capabilities.  The reason for this detour is that using the etching system will be better optimized is the samples are as free of impurities (surfactant and other junk besides the spheres) as possible because it will create inconsistencies in the etching depth and performance.  Once we have determined that we have obtained as clean a sample as possible we are going to etch again at a length of time longer than 30 seconds but shorter than 5 min.  This should yield pillars and hopefully those pillars have a fine enough relief (edge on the top) that we can start using AFM to view surfactants on them!
I'll admit that we are moving slower than I had hoped, but at this point moving slowly is better than not moving at all! 

Tulsa Trenches and OU Terraces

Yesterday in Tulsa went very well.  Despite the e-beam technician being on vacation until next week I have still been able to make some good strides in sample preparation.  The AFM tech at TU had some trouble getting a good PMMA layer depth reading on the samples from last week. He said they were in the neighborhood of 50 nm, which is about a third of what we were expecting based on the notes of the students previously working on this type of set up.  I have found some other protocols online that suggest that 50 nm is actually right on the money.  It was stated in the proposal that as long as the wall height was 20 nm or more it should not affect the surfactant adsorption, and the lower the wall height the less it will interfere with the AFM tip when gathering images after surfactant adsorption so 50 nm is actually really good.  I'm a tad nervous because the PMMA solution they have had me using at TU was the same that the group before me was using, which has an expiration date about 4 years ago.  However, it should not cause problems for the purposes we need it for.
I have some trouble making sure that the silicon pieces are microscopically smooth (using the right cleaning solution as well as a plasma cleaner) and this may be what's causing the small imperfection that can be seen in the film.  The debris causing a wake pattern on the surface during the spin coating and I'm not sure it's a problem at this point as we can choose which area to use for the formation of trenches.
I will be returning next Thursday to continue the work and the e-beam tech should be back and we can see if we can get some trenches made!
On the other side of the project, I will be meeting with the OU researcher who has been helping me with nanosphere lithography and discuss the SEM micrographs and hopefully the week after we can try another run of etching with smaller spheres!

Channel Formation

Last week I was able to complete a preliminary sample of a layer of PMMA on silica.  I am still awaiting the results as to how thick the layer was deposited, but hopefully somewhere in the neighborhood of 150 nm (according to the protocol I was attempting to replicate).  I really enjoyed working with the graduate assistants and professors at TU because they were very friendly and helpful.  They could have just have easily left me to my own devices in a foreign laboratory but they helped me find equipment and supplies early one and I was able to figure out the rest as the day went on.  All in all,so far, it has been a pleasant and productive experience and I look forward to continuing my collaboration with them. I will be returning to Tulsa this Thursday to continue the preparation work and when the e-beam technician returns the week afterwards we will be able to form the channels!

Getting somewhere

Going to the University of Tulsa on Thursday to begin preparation on the samples to be used for the trenches samples!!  I'm slightly nervous to be working in another lab, just as I was for coming into the University of Oklahoma I suppose, only this time it's for short spurts.  Every lab has their own house rules that they expect everyone to follow and depending on who is working in the that lab and what else is being performed it can be very different and make beginning work slow.  Because I want to be done with this phase of the research by the end of the summer I am excited that it is moving along but nervous that it may take longer (months) than I want.  I am very confident in the supervisor who will be showing me the ropes there and am looking forward to learning from him and others at TU.  Happy Independence Day!

Channel sample preparation

The e-beam is ready to begin use for creating channels to observe the effects of sidewall confinement on adsorption!  Making plans to go to University of Tulsa this week to begin preparing samples so that next week (or the week after depending on scheduling) the e-beam can be used in order to create the channels.
Work to create the nanopillars is still continuing and I am anticipating seeing results after the next etching session which is set tentatively for the week after the fourth of July.  It will be easier, I believe, to move on having both of these samples completed.  I think this because the step afterwards will be to use liquid cell AFM to observe surfactant on the surface of these substrates and focusing on that area, particularly the use of the AFM and developing my skill with it, and not trying to complete the fabrication of another sample will simplify things.  Just happy to know that things are still moving along!  

Taking a small step back can be a good thing

After conferring with one of the research scientists helping me with the etching, the methanol soak may not have removed anything as we had hoped.  It is still looking promising that a sample of nanopillars, usable or not, will be completed before the end of June.  So either way I am to be moving forward, which is good.  On the other hand I am still feeling as though if these don't work or are not up to the specifications that we need them that a lot of time has been ill spent.  Looking on the bright side, it has given me opportunities to learn about what surface we are looking for and look for different approaches at getting it.  In other words, if it does not work then I have a few other options that I can switch to without having to spend more time researching.
I still have not heard back from the contact that has offered to help us with the channels, but with any luck that end of the project will also be up and running by the end of June as well.
As my summer class also come to an end, I'm feeling the pressure from several different sides to produce results and the feeling of being overwhelmed has crept up more than a few times.  However, taking one thing at a time and making sure to manage my time efficiently is definitely keeping me sane.  There is something to be said for a well used day planner.

The Waiting Game

Have been awaiting responses from contacts regarding e-beam lithography and the etching for quite a while now.  I have said it before, but one of the most frustrating things about research is coordinating schedules with more or equally busy people.  To use try and use my time wisely I have continued reading papers about self assembled monolayers and looked for ways to improve the sphere layering techniques I have come up with so far.  The 50 nm beads, while a monolayer, are still the hardest to perfect.  I feel as though there may be some limitations with my set up that prevent the further improvement upon the smallest beads.  However, oxygen etching can be used to shrink spheres that are already on the smaller end of the spectrum (100 nm) to get spheres are 50 or smaller.  The pillars will be spaced further apart if this route is used but that may even work to our advantage in limiting the amount of interaction between sphere monophologies which will be forming on the pillar surfaces.  

I am going to continue trying to reach my contacts in order to move forward as quickly as possible.  In previous posts I have stated my goals for June.  While there is still time to complete these goals, I am currently at the mercy of others and I am not enjoying this goals being at the mercy of the schedules of others.  I will continue working to those goals anyway and make new ones when necessary to work towards getting our questions answered.