A semiconductor device is an electronic component in which electrical conductivity is between conductor and insulator, with the specific electrical characteristics of the semiconductor material, thus it is usually used to perform a certain specific function;
Diode (rectifier diode):Gunn diode, IMPATT diode, Laser diode, Zener diode, Schottky diode, PIN diode,Tunnel diode, Light-emitting diode, Photo transistor, Photocell, etc.
Three-terminal devices: Bipolar transistor, Field-effect transistor, Darlington transistor, Insulated-gate bipolar transistor, Unijunction transistor, Silicon-controlled rectifier, etc.
Four-terminal devices: Photo coupler (Optocoupler), Hall effect sensor (magnetic field sensor), etc. [From Quora]http://www.58pcba.com/data/upload/image/201908/629f0e48ecaa664657d0dccf6a970458.jpg