✔ Silicon Diode Theory

Current flows from the negative terminal of the battery to the n type and on through the p type and then returns to the positive terminal of the battery. Silicon diodes require more voltage to conduct current.

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The principle of four layer pnpn switching was developed by moll tanenbaum goldey and holonyak of bell laboratories in 1956.

Silicon diode theory. Thus if an external voltage greater than and opposite to the built in voltage is applied a current will flow and the diode is said to be turned on as it has been given an external forward bias. Mackintosh of bell laboratories in january 1958. Pn junction diodes can be obtained in a number of semiconductor materials the earliest diodes tended to be made from germanium but most of them today are silicon diodes.

It takes 07 volts to create a forward bias situation in a silicon diode. The theory of solar cells explains the process by which light energy in photons is converted into electric current when the photons strike a suitable semiconductor device. The chief difference between germanium and silicon diodes is the voltage at which electric current begins to flow freely across the diode.

When the externally applied forward voltage across the diode becomes more than the forward barrier potential the free majority charge carriers start crossing the barrier and contribute the forward diode current. For silicon diodes the built in potential is approximately 07 v 03 v for germanium and 02 v for schottky. A silicon controlled rectifier or semiconductor controlled rectifier is a four layer solid state current controlling device.

The practical demonstration of silicon controlled switching and detailed theoretical behavior of a device in agreement with the experimental results was presented by dr ian m. The diode is simple in its basic concept being formed from the junction of n type and p type materials although in reality the manufacture and theory of operation are more complex. For silicon diodes the forward barrier potential is 07 volt and for germanium diodes it is 03 volt.

Diode theory the diode is comprised of a p type material combined with an n type material such as. Pn junction theory a pn junction is formed when an n type material is fused together with a p type material creating a semiconductor diode in the previous tutorial we saw how to make an n type semiconductor material by doping a silicon atom with small amounts of antimony and also how to make a p type semiconductor material by doping another silicon atom with boron. A germanium diode typically begins to conduct electric current when voltage properly applied across the diode reaches 03 volts.

In this lab you are to measure i v characteristics of rectifier and zener diodes in both forward and reverse bias mode as well as learn to recognize what mechanisms cause current flow in each region of diode operation. Silicon point contact diodes made an important contribution to radar in world war ii detecting giga hertz radiofrequency echo signals in the radar receiver. The concept to be made clear is that the point contact diode preceded the junction diode and modern semiconductors by several decades.

The diode is commonly said to have a forward threshold voltage above which it conducts and below which conduction stops.