Editing X-ray fluorescence (section)

====Si(Li) detectors====
These consist essentially of a 3–5&nbsp;mm thick silicon junction type p-i-n diode (same as PIN diode) with a bias of −1000 V across it. The lithium-drifted centre part forms the non-conducting i-layer, where Li compensates the residual acceptors which would otherwise make the layer p-type. When an X-ray photon passes through, it causes a swarm of electron-hole pairs to form, and this causes a voltage pulse. To obtain sufficiently low conductivity, the detector must be maintained at low temperature, and liquid-nitrogen cooling must be used for the best resolution. With some loss of resolution, the much more convenient Peltier cooling can be employed.<ref>{{cite book|url=https://books.google.com/books?id=667SJf95AFAC&pg=PA559|page=559|title=Transmission electron microscopy: a textbook for materials science|volume=2|author=David Bernard Williams|author2=C. Barry Carter|publisher=Springer|date=1996|isbn=978-0-306-45324-3}}</ref>