Gold-Coated Substrates
Does Platypus clean the substrates before coating them with gold?
All of our substrates are cleaned with an oxygen plasma prior to coating.
Do I have to be careful not to scratch the gold on the substrates?
Gold is a very soft metal and will scratch easily. Avoid touching the gold thin film as much as possible by holding the substrates at their cross-section.
Why does Platypus use titanium as the adhesion layer?
We use titanium, not chromium, as the adhesion layer, because chromium diffuses into the overlying gold over time more quickly than titanium.
Which substrate provides the smoothest surface?
The Platypus Template Stripped Gold Chips have the lowest roughness (at or around atomic flatness). We also sell 2000 angstroms of Au on atomically flat Mica, so when annealed properly it can produce atomically flat terraces of the <111> crystalline orientation. Hydrogen flame annealing of the Au coated Mica is the most popular procedure to achieve this. Most of our as-deposited Au coated substrates will have an RMS roughness of 2-4nm.
Why might I want atomically flat gold on my substrates?
Smoother Au surfaces can produce SAMs with less defects. Also, atomically flat Au with single <111> crystalline terraces do not have grain boundaries, which makes microscope imaging of chemistries, SAMs, biologics, etc. on the nanoscale much easier to depict.
What is the orientation of the gold surface on the substrates?
All PVD thin metal films, except for epitaxial grown films in a special magnetron sputtering PVD system, are highly polycrystalline. The tendency for the Au films is to assume a <111> orientation and when annealed properly the Au films can grow <111> orientated single crystal terraces up to ~1 micron large.
Can I purchase substrates coated with just titanium (without gold)?
Yes, we can custom coat substrates with just titanium. The titanium will oxidize though once brought up to atmospheric conditions. This will be a custom order.
Can I purchase substrates that are gold coated, but without a titanium adhesion layer?
Yes, we can coat substrates with just a gold thin film and no titanium adhesion layer. This can be done with the understanding that the adhesion of the gold to the substrate without a titanium adhesion layer will be very poor. This will be a custom order.
Do I need to clean the gold coated substrates before putting into an ethanol thiol solution?
If you leave the Au coating in the thiol solution for 16+ hours there is no real need to clean the Au coating beforehand. If you are only leaving the Au coating in the thiol reaction for 1-2 hours, it is recommended that the Au coating is cleaned prior to thiol SAM functionalization.
How should I clean my gold coated substrates?
The three best and most common ways to clean a Au coating are: using a plasma cleaner, a UV/ozone cleaner, or using a chemical cleaning that removes organic contamination (e.g. Piranha solution). If Piranha solution or any other strong acid is used to clean the Au coating, do not leave the Au thin films in it too long otherwise it can damage the substrates.
What are the glass specifications for the microscope slide substrates?
Glass Description and Specifications:
Can we get glass coated in different sizes other than standard glass microscope slide size?
Yes, as long as it is not smaller than 1 cm on a side or larger than 6.5 inches on a side. Usually, we also try to restrict the thickness of the substrates to between 0.1 and 3 mm, but depending on the substrate shape and weight this range could be adjusted. This will be a custom order, so a quote will need to be generated based on your requirements.
Can I cut the mica?
Gold coated mica may be cut with a sheet metal bench shear or a sharp pair of scissors. We do not recommend using a scalpel or knife as they might tear the coating along the edge of the mica.
What type of mica is used?
We use the highest grade of Mica, V1, and it is cleaved before coating to reveal a very clean and flat surface for coating.
What is the surface flatness of the test grade silicon wafers you deposit on?
Typical GTIR (Global Total Indicated Readout ? measured from an imaginary plane across the center of the wafer to the top of the surface of the wafer) is <15 micron.
What are the other properties of the test grade silicon wafers you use?
Properties:
Do you coat any other kinds of silicon wafers?
We generally have a small amount of prime grade silicon wafers in stock, and can usually order any wafer a customer may specify. This will be a custom order, so a quote will need to be generated based on your requirements.
What type of glass are the coverslips made of?
Borosilicate glass.