on friday afternoons from 1 to 5 i have a class under prof. vounckx on the physics of semiconductor technologies and devices. as you can well understand it's not quite the ideal time to have such an extremely long class - sunny friday afternoons spent in the basement of building k! gah! which is probably why the professor has been making an effort to make classes enjoyable on top of the fact that he has to make manufacturing of microchips sound interesting.
he's been making a lot of jokes in class but the one i found really funny by far was his idea on an agatha christie-ish murder plot by using gallium arsenide chips to execute a murder. the topic of that class was about how to make a doped layer on a GaAs substrate. one could grow layers by either of the three processes: buried layer diffusion, epitaxy, or ion implantation. of the three, you could only grow a layer on a GaAs substrate by epitaxy because the other two (both for diffusion and the annealing step of the ion implantation process) would require very high temperatures (about 1000 degree celcius). of course we don't want very high temperatures when processing GaAs since arsenic would out-diffuse at high temperatures and, as we all know, arsenic is a very poisonous substance.
soooo that's the joke, na-explain ko na. labyu. haha. of course to carry out your murder plan via a GaAs chip you'd need to have a way to heat it to more than 600 degrees to free the arsenic. but let's leave that bit for agatha christie to figure out haha.
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