Si-Avalanche-Photo-Diode (APD) with space charge distribution under reverse voltage (top), and corresponding electric field distribution (bottom).
<a href="//commons.wikimedia.org/wiki/User:%D0%94.%D0%98%D0%BB%D1%8C%D0%B8%D0%BD" title="User:Д.Ильин">Д.Ильин</a>: vectorization, translation
<a href="//commons.wikimedia.org/wiki/File:APD2_German.png" title="File:APD2 German.png">File:APD2 German.png</a> by <a href="//commons.wikimedia.org/w/index.php?title=User:Kirnehkrib&amp;action=edit&amp;redlink=1" class="new" title="User:Kirnehkrib (page does not exist)">Kirnehkrib</a>