Why depletion region is formed

The diffusion does not occur indefinitely and it stops after a quick span of time and the depletion region is said to be completely formed. Take a look at the figure below to understand how this happens. In forward bias, the P-type is connected with the positive terminal and the n-type is connected with the negative terminal. This reduces the width of the depletion zone. Connecting the P-type region to the negative terminal of the battery and the N-type region to the positive terminal corresponds to reverse bias.

If a diode is reverse-biased, the voltage at the cathode is comparatively higher than the anode. Therefore, no current will flow until the diode breaks down. The connections are illustrated in the diagram to the right. Your email address will not be published.

Save my name, email, and website in this browser for the next time I comment. Skip to main content. Leave this field blank. Search form Search. Formation of a PN-Junction Overview Joining n-type material with p-type material causes excess electrons in the n-type material to diffuse to the p-type side and excess holes from the p-type material to diffuse to the n-type side. Movement of electrons to the p-type side exposes positive ion cores in the n-type side while movement of holes to the n-type side exposes negative ion cores in the p-type side, resulting in an electron field at the junction and forming the depletion region.

The total charge formed at the p-n junction is called barrier voltage, barrier potential or junction barrier. Potential barrier is the potential difference or junction voltage developed across the junction due to migration of majority charge carriers across it when p-n junction is formed. It opposes further migration of majority carriers across the junction due to this junction voltage. Depletion Region Details Filling a hole makes a negative ion and leaves behind a positive ion on the n-side.

A space charge builds up, creating a depletion region which inhibits any further electron transfer unless it is helped by putting a forward bias on the junction. Barrier Potential: The electric field formed in the depletion region acts as a barrier. External energy must be applied to get the electrons to move across the barrier of the electric field. The potential difference required to move the electrons through the electric field is called the barrier potential.

In semiconductor physics, the depletion region, also called depletion layer, depletion zone, junction region, space charge region or space charge layer, is an insulating region within a conductive, doped semiconductor material where the mobile charge carriers have been diffused away, or have been forced away by an ….

Depletion is an accrual accounting technique used to allocate the cost of extracting natural resources such as timber, minerals, and oil from the earth. Like depreciation and amortization, depletion is a non-cash expense that lowers the cost value of an asset incrementally through scheduled charges to income. Depletion region or depletion layer is a region in a P-N junction diode where no mobile charge carriers are present. Depletion layer acts like a barrier that opposes the flow of electrons from n-side and holes from p-side.

The depletion region acts like a wall between p-type and n-type semiconductor and prevents further flow of free electrons and holes. Hence, the regions nearby the p-n interfaces lose their neutrality and become charged, with positive charge on n-side and negative charge on p-type.

Thus, the electric field in the depletion layer of an unbiased p-n junction is from n-side to p-side. The barrier potential of germanium is approximately 0. These values cannot be measured directly and appears across the space charge region of the junction. In order to produce current conduction, the barrier potential of a P-N junction must be overcome by an external voltage source.