Am I really a chemist??? by Dr. Arnab Bhattacharya Posted on 1st October 2011
That was the first thought that crossed my mind when I got a call to be on the panel for the Best Chemistry Teacher Award. I mean, they probably are looking for someone with a proper chemistry training and degree, the stereotype you'd think who'd wear lab coats and work with test tubes... Why would they want a bloke with an engineering undergrad and a Ph.D. in physics working on semiconductor devices? But hang on, what do I really do?
Well, for the past many years, I've been synthesizing semiconductor materials for optoelectronics applications, for example gallium nitride (GaN). The way this is most easily done is by using an organometallic compound like trimethylgallium and making it react with ammonia - at high enough temperatures these molecules break up, the gallium reacts with the nitrogen to form GaN, which deposits as thin layers on a substrate leaving methane as a byproduct. Legitimate chemistry I guess.
What I however find really exciting is that areas like semiconductor optoelectronics are meeting grounds for many traditional disciplines. To make a tiny diode laser or a bright white LED requires not only organometallic chemistry, but also inputs from physics, materials science, electrical engineering, and sometimes even biology. Let's see. A typical LED has very thin layers of different semiconductor materials arranged to form a complex sandwich structure. You need to understand quantum physics as these layers are so thin that electrons get tightly confined in them and their properties are modified by quantum mechanics in potentially useful ways. Making the ultra-thin sandwich means arranging different materials carefully on top of each other - there's always strain and layers tend to crack - understanding stress and dislocations is important, all standard materials science. Of course you want to put in current and get the device to put out light - this means worrying about low-resistance electrical contacts to get the current in, and waveguide structures to channel the light out - all in the domain of electrical engineering. And guess what, the key to getting the catalysts for our indium arsenide nanowires to stick to the substrate came from a conversation with a biologist at the tea-table - we put an intermediate layer of poly-L-lysine, stuff derived from an amino acid that's used in tissue culture. Interdisciplinary enough?
So am I a chemist? Well, I'll leave that for you to decide...Personally, I think, as scientists we study the world around us, try to make some sense of it, and learn something. A cell under a microscope or a star in a galaxy far away doesn't care for our classifications and subdivisions of physics/chemistry/biology etc. We're all scientists!