The Schottky diode, also known as Schottky barrier diode or hot-carrier diode, is a semiconductor diode formed by the junction of a semiconductor with a metal. It has a low forward voltage drop and a very fast switching action. The cat's-whisker detectors used in the early days of wireless and metal rectifiers used in early power applications can be considered primitive Schottky diodes.
Various Schottky-barrier diodes: Small-signal RF devices (left), medium- and high-power Schottky rectifying diodes (middle and right)
1N5822 Schottky diode with cut-open packaging. The semiconductor in the center makes a Schottky barrier against one metal electrode (providing rectifying action) and an ohmic contact with the other electrode.
HP 5082-2800 Schottky Barrier Diodes for General Purpose Applications
SS14 Schottky diode in a DO-214AC (SMA) package (surface mount version of 1N5819)
Walter Hans Schottky was a German physicist who played a major early role in developing the theory of electron and ion emission phenomena, invented the screen-grid vacuum tube in 1915 while working at Siemens, co-invented the ribbon microphone and ribbon loudspeaker along with Dr. Erwin Gerlach in 1924 and later made many significant contributions in the areas of semiconductor devices, technical physics and technology.
Schottky, c. 1920