Semi conductors: Materials having exactly four electrons in their outermost orbit. Germanium and silicon are two examples. Related posts: Personnel Management Operative Functions Administrative Role of PM Competency HR Management Role Change Personnel Policies Personnel Procedures Appealed Policies Implied Policies Specific Policies Personnel records Research Pure research Personnel research Attitude or Opinion Survey Turnover Secondary research Applied research Personnel audit Read more articles Previous PostSecondary cell/battery Next PostSensor