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Over the summer, I was a research assistant at the local university's Surface Sciences lab. Now, the group's small (<10 people), and I have sold my soul to the professor (but at least I have guaranteed summer jobs and a potential PhD spot, so yay?), and I had lots of fun!

The basics:
We measure stuff that happens in the very surface layers of a material. We also grow nanometer-scale thin films (with ALD) and create functional coatings for materials (for instance by silanization). Our main means of measurement is XPS, though one colleague of mine was using the ellipsometer for measuring ALD layer thickness, and we've recently acquired a portable adhesion tester.

XPS = X-ray Photoelectron Spectroscopy
There is a thing called the photovoltaic effect: when one shines a light on a material, it emits electrons. The energy of the light, hf, transfers completely to an electron it hits. Part of this energy is spent getting the electron out of the atomic nucleus' orbit (=the energy with which the nucleus held on to the electron, aka the binding energy B), and the rest of the energy is then the electron's kinetic energy K. With a complicated system of lenses (= electric fields) we can capture the electrons emitted from the sample and record their kinetic energies (they go through a hemisphere with a magnetic field, and qṿ×Ḅ means that electrons with different energies have different radii with their paths).
Then, the magic: hf=K+B, thus B=hf-K, which means that we can find out the binding energy! Now, different elements have different binding energies for each electron orbital (Oxygen and Carbon 1s electrons have vastly different energies, and we can detect the splitting between Copper 2p3/2 and 2p1/2), so we can figure out the chemical composition, and the binding energy changes depending on what compound the element is in! Silicon 2p (in metallic Si) and Silicon 2p (in SiOx) have a difference of a few electron volts!

ALD = Atomic Layer Deposition
Basically, precursors (volatile compounds) are in bottles, from which the vapor is pumped into the reaction chamber, where the substance attaches itself onto any surface it comes in contact with, and then from (say) trimethylaluminum and water comes a thin film of aluminum oxide.


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