7/08/13 & 7/09/13

7/08/13 & 7/09/13

Things to do:

1. We still need to find out if the SiO2 layer is the problem. Using the wafers with the newly grown SiO2 layer we can try the same old pattern with spot size 1 @ 1.5kV. If the pattern shows up we know we need a layer of SiO2 at least 100-300 nm thick.

2. Try a new pattern with horizontal and vertical lines to see which work better at aligning CNTs

Things that were done:

1. We saw the pattern on the wafer with the thicker layer of SiO2. We now know that we need a thicker layer of SiO2 (100-300nm thick) in order for the resist layer to stick to the wafer.

2. We used a pattern with 2 horizontal lines 25 microns in length, 2 horizontal lines 50 microns in length, 5 vertical lines 5 microns in length, and 5 vertical lines 10 microns in length.
     -We found that the vertical lines had some tubes aligned at an angle like the ones found on the horizontal lines. The vertical lines also had entire CNTs stuck on the lines. This means the tubes were oriented in the same direction as the vertical lines. This could be very useful for aligning all of the tubes in the same direction and at specific locations. We will try more patterns with vertical lines in the next few days.

3. PMMA had the tendency to stick more nano tubes on it surface, but not necessarily the pattern itself. We decided to use EL6 as our resist layer since we want the CNTs on the lines only and not the surrounding area.