So, if we move from the p to the n region, the electric field goes negative, reaches a minimum negative value and on reaching the edge of the n side, it starts increasing, and is 0 on the boundary of each of the p and n regions. So, the absolute value of electric field is maximum at the metallurgical junction.
Why electric field is maximum at junction?
As a result of high electron field across the junction under reverse biased condition, the breakdown of charge carriers takes place. Therefore, current increases rapidly. This is because ϵ=−drdV, when both p and n regions are heavily doped, a depletion layer is very thin. So, electron field is maximum at the junction.
Why an electric field is produced in a depletion region of a pn junction?
After joining p-type and n-type semiconductors, electrons from the n-region near the p-n interface tend to diffuse into the p region. As electrons diffuse, they leave positively charged ions (donors) in the n region. … Thus, the electric field in the depletion layer of an unbiased p-n junction is from n-side to p-side.
What is the maximum electric field in a PN junction?
A silicon (ni = 1010 cm–3) p-n diode has a maximum electric field of -106 V/cm and a depletion layer width of 1 mm. The acceptor density in the p-type region is four times larger than the donor density in the n-type region.
How does the electric field vary within the depletion region in pn junction diode?
The maximum electric field occurs at the junction between the p- and n-type material. … In other words, if the electric field is confined to the depletion region, then the net charge in Region II must be zero, and hence the negative charge and the positive charge must be equal.
At which point electric field is maximum Why?
Again, the maximum electric field is at the center of depletion region only if the doping levels of p- and n-type are equal.
How do I get rid of depletion region?
Forward bias (applying a positive voltage to the P-side with respect to the N-side) narrows the depletion region and lowers the barrier to carrier injection (shown in the figure to the right).
How electric field is created across pn junction?
PN Junction Distance
Then the presence of impurity ions on both sides of the junction cause an electric field to be established across this region with the N-side at a positive voltage relative to the P-side.
What causes the depletion region?
The depletion region is caused by the diffusion of charges. … The holes and the electrons diffusing towards each other combine near the junction. In doing so positive and negative ions are formed. The pair of positive and negative ions at the junction forms the dipole.
What is meant by depletion region?
[ dĭ-plē′shən ] A region in a semiconductor device, usually at the juncture of P-type and N-type materials, in which there is neither an excess of electrons nor of holes. Large depletion regions inhibit current flow.
Why an electric field is produced in space charge region?
When a bulk semiconductor is in contact with a different semiconductor, metal or electrolyte, a space charge region is formed at the interface to equalize the Fermi levels. The generation of space charge region is important to separate the photogenerated electrons and holes toward opposite directions.
What is width of depletion region?
The physical width of the depletion region in a typical Si diode ranges from a fraction of a micrometer to tens of micrometers depending on device geometry, doping profile, and external bias. Figure 11.4.
What is full depletion voltage?
At full depletion the diode has full sensitivity to detect particles. The depletion voltage is normally defined as the bias voltage required so that the region de- pleted of free carriers reaches through the whole of the semiconductor bulk.
How does the depletion region behave?
In the depletion region, an electric field exists that quickly sweeps out electron-hole pairs that may be thermally generated and reduces the equilibrium concentration of the charge carriers to exceedingly low levels. … This region, called the depletion layer, behaves as an insulator.
How does the width of depletion region of pn junction?
Width of the depletion region in a P-N junction decreases when it is forward biased whereas increases when it is reversed biased.
What is the order of reverse current in a diode?
The very small current flows through the diode when the diode is in the reverse-biased state is called the reverse current of the diode. The reverse saturation current of a Germanium diode is of the orders of micro-amperes. While the reverse saturation current of a silicon diode is of the order of nano amperes.