There are a couple ways it might be done. First - it is possible to sputter a thin layer of Fe metal on glass (Magnetron Sputtering) http://www.electrochemsci.org/papers/vol10/100705488.pdf
the coatings are thicker than you want but shorter times would solve that.
I believe you can also form a Fe by reduction of an oxide later on the surface. It may be difficult with Fe but works with Cu oxides. There are some papers on the subject - simply google Reduction of FeO to Fe