“Unlocking the Future: How a Simple Discovery Revolutionized Technology and Changed Our Lives Forever”
When an external current is applied from the N to the P side – that is, in the direction of the internal diffusion current – it will flow freely through the diode. If, however, the current is applied in the opposite direction, it will cause the depletion region to grow, forming a barrier through which the current cannot flow. A PN junction thus performs the same function as a vacuum tube diode, allowing current to only flow in one direction.
In a metal-semiconductor junction like a crystal detector, the semiconductor is N-type while the metal acts as the P-type semiconductor, with the interface between the two forming a depletion region or Schottky barrier like in a PN junction.
The PN junction diode was discovered in 1939 by Bell Labs researcher Russel Ohl when he accidentally cut a section of a silicon ingot across the PN junction and noted its rectifying qualities. During the Second World War, self-contained Schottky and PN diodes developed for use in military radars, as vacuum tubes could not operate on the required frequencies. These devices were the first truly solid-state miniaturized electronic components, and pointed the way toward the use of semiconductors to create a new, efficient analogue to the triode vacuum tube.
Interestingly, a design for a type of semiconductor-based electronic switch now known as a Field-Effect Transistor or FET was patented as early as 1925 by Austrian-American inventor Julius Lilienfeld. However, as sufficiently pure semiconductors were not available at the time, Lilienfeld was unable to construct a working prototype, and his design remained little more than a footnote in the history of electronics. It would not be until after the Second World War that his ideas would finally become a reality.
Post Comment