Schottky Diode
metal-semiconductor junction diodes
Schottky Diode
Schottky diode
A very high speed bipolar junction transistor having a metal-semiconductor emitter base junction instead of a semiconductor-semiconductor emitter base junction.
That is a DIODE, which can be of any of these types:P-N junction (shown above)point contactschottky barrier (i.e. metal-semiconductor junction)
A Shockley diode uses a metal-semiconductor junction instead of a p-n semiconductor-semiconductor junction. This results in a device with a much lower forward bias voltage drop and much faster switching times.
It can be either a junction or point contact diode built with semiconductor material. there are many types depending on intended usage.junction diode is produced as described in its name by forming a junction in the semiconductor by using opposite types of dopant impurities.point contact diode is produced as described in its name by taking a semiconductor base and pressing a sharp metal point on its surface.A few of the types of semiconductor diodes are: small signal, power rectifier, zener, tunnel, gunn, etc.
An ordinary semiconductor diode uses a P-N junction, but when reverse biased it takes a period of time to remove the current carriers from that junction to create the depletion region that blocks reverse conduction. A Shockley diode instead uses a P semiconductor-metal junction, which removes the current carriers much faster from the semiconductor allowing the device to switch much faster. It also has a much lower forward bias voltage than an ordinary diode. In many ways it is similar to the previous point contact diodes (a piece of semiconductor like galena or germanium with a metal "cat's whisker" point contact) in operation, but is more reliable and easier to mass produce.
The first modern semiconductor diode was made with germanium. These diodes were invented in ww2 for RADAR. But before that semiconductor diodes were made with galena (lead sulfide), copper oxide, and selenium. I have no idea which was "first".
junction diodeThere are two other ways of making a simple solid state diode:point contact diode, one piece of semiconductor with a sharp metal needle point touching itmetal-semiconductor diode, a layer of metal over a layer of semiconductor
A p-n junction (or a metal-semiconductor junction) with rectifying behaviour is an electronic device which allows a one-way only current flow (between the two semiconductor regions, or between the metal and the semiconductor). An ohmic contact in a metal-semiconductor junction is realized by lowering the potential barrier (allowing electrons to easily migrate into the metal) and by increasing the doping levels in the semiconductor (more than 10^18 cm^-3): this way the potential barrier, that should stop electrons from migrating into the semiconductor, is confined in a very small region making it possible for electrons with low energy to pass through it (tunneling effect). This means that in a ohmic contact current can flow both ways; such a device apparently works like a resistor with a low resistance, hence the "ohmic contact" name.
I think its related to junction of two dissimilar semiconductor (or semiconductor and metal) and not only a semiconductor. well when two opposite nature semiconductor (hetero or homo) are joined to form a junctions they allow the flow of current in one direction while blocks it in other direction. The applied bias V which will cause the current flow is called forward bias and the current flowing through the junction forward bias current.