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# how is the breakdown voltage related to doping level of a diode

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## 1. How is the breakdown voltage related to doping level of a diode?​

The maximum reverse bias voltage that can be applied to a p-n diode is limited by breakdown. ... The resulting breakdown voltage is inversely proportional to the square of the doping density if one ignores the weak doping dependence of the electric field at breakdown.

Vysockaya Sofya Jan 8, 2021

## 1. How is the breakdown voltage related to doping level of a diode?​

The time for answering the question is over

The maximum reverse bias voltage that can be applied to a p-n diode is limited by breakdown. ... The resulting breakdown voltage is inversely proportional to the square of the doping density if one ignores the weak doping dependence of the electric field at breakdown.

203 Sachs Jan 8, 2021

स्रोत : expertinstudy.com

## What is the relation between breakdown voltage and doping concentration?

Answer: When we heavily dope the diode then the depletion width decreses which leads to the tunneling of carriers across the width and when we increase the reverse voltage the depletion width increases and then there will be strong electric field across pn junction. Because of this high electric ...

What is the relation between breakdown voltage and doping concentration?

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Sort Thanmayee V

Studied at B. Tech. (ECE) (Graduated 2017)4y

When we heavily dope the diode then the depletion width decreses which leads to the tunneling of carriers across the width and when we increase the reverse voltage the depletion width increases and then there will be strong electric field across pn junction. Because of this high electric field the covalent bonds in the pn junction breaks and releases valence electrons which will be excited to conduction band producing high reverse current and breaks down the diode which is called zener breakdown.

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Why does an increase in the doping concentration of a diode decrease its breakdown voltage?

Originally Answered: Why do increases in the doping of a diode decrease its breakdown voltage?

The width of the depletion region in a p-n junction diode is inversely proportional to the doping concentration of the n and p sides. So, as doping increases, the depletion region width becomes narrower.

Electric field is given by E = -dV/dx, that is by the gradient of the barrier potential, for a p-n junction diode.

Thus, smaller the width of the depletion region, larger will be the electric field.

This high electric field will exert a force on the electrons and holes bounded via covalent bonds, and cause them to move across the junction by breaking the bond.

Thus, large number of electron-hole p

Neev Shir

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How is a transistor useful as compared to another switch?

A transistor is an electrically controlled switch which has many advantages and disadvantages over normal physical contact switches.

A physical switch is limited to the speed of your hand. If the human hand can't switch switches faster than 3 Hertz, the switching speed will be limited to 3 hertz.

A physical switch has two states: On and Off. Either no voltage or the Source Voltage. On the other hand varying the base current of a transistor will cause the transistor to act not only as a switch, but also as a variable resistor.

Relative to (1), a transistor can switch from 0 hertz to around several

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Ye Wai Yan Oo

Former Student at Yangon Technological University5y

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What is the breakdown voltage of a pn junction?

I’ll explain that in simple terms. PN junction diode is kind of semiconductor device mostly very useful in many analog circuits. It allow to pass current through it when you connect it ends properly(Acutally there is no proper or improper way in that)

In above picture, there is a circuit symbol for pn junction diode. If you connect the anode to positive terminal and cathode to negative terminal of a dc source, the current will flow through.(I meant that ‘a proper way’) and it is called forward biased. But if you reverse the connection to positive to negative, the current won’t flow through and

Malar Chellasivalingam

Studied at Queens' College, Cambridge (Graduated 2021)5y

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Where do the ions come from in a pn junction diode?

When a semiconductor is doped (added) with trivalent impurity such as Boron (B) or Aluminum (Al), it becomes a p-type semiconductor. When a semiconductor is doped with pentavalent impurity such as Phosphorus (P) or Arsenic (As), it becomes an n-type semiconductor.

A p-type semiconductor consists of holes as the majority charge carriers, and an n-type semiconductor consists of electrons as the majority charge carriers.

How a pentavalent impurity forms bond in a semiconductor

When an atom of 5 valence electrons (pentavalent impurity) is added to the semiconductor, four of the valence electrons in t

Rushiraj Moteria

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What is the effect of temperature on a Zener breakdown voltage and an avalanche breakdown voltage?

Zener breakdown and temperature effect:

Zener breakdown occurs when the electric field is much stronger to torn the electrons from valence band to conduction band. As temperature increases , band gap decreases so less electric field is required to torn electrons from valence band to conduction band. So zener breakdown voltage decreases as the temperature increases. Thus zener breakdown is negative temperature coefficient.

Avalanche breakdown and temperature effect:

In avalanche breakdown , a bunch of electrons knocks out other electron to conduction band creating electron hole pair. Due to increa

स्रोत : www.quora.com

## Variation of breakdown voltage with doping concentration for diodes...

Download scientific diagram | Variation of breakdown voltage with doping concentration for diodes with and without edge termination ( t = 0 : 7 m ) .  from publication: Design rules for field plate edge termination in SiC Schottky diodes | Schottky Diodes, Silicon Carbide and Wide Band Gap Semiconductors | ResearchGate, the professional network for scientists.

Fig 5 - uploaded by Marc Tarplee

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## Variation of breakdown voltage with doping concentration for diodes with and without edge termination ( t = 0 : 7 m ) .

Source publication +2

Design rules for field plate edge termination in SiC Schottky diodes

Article Full-text available Jan 2002 Marc Tarplee Vipin Madangarli Quinchun Zhang Tangali Sudarshan

## Contexts in source publication

Context 1

... with a doping of cm . The field plate consists of a metal-overlap over an oxide layer. To make the simulations more realistic, an interface charge density of cm was added to the oxide/SiC interface. P-type SiC devices were simulated because the authors were already examining p-SiC Schottky diodes to determine if they could be used for high power applications. The epitaxial layer thickness , oxide thickness , and the overlap , were varied to as- certain their effects on the breakdown voltage. is the radius of the metal contact. In particular, the epilayer thickness was varied to ensure that there is no punch-through up to the breakdown voltage during the simulations. The simulation results show that the maximum electric field in the epitaxial layer of both structures occurs directly under the corner of the Schottky contact. The electric field directly under the center of the Schottky contact is smaller than the value under the corner and is very close to the value computed from the “parallel plate” approximation that appears in many texts [1], [11]. The relationship between the doping concentration and the peripheral and central electric fields that occur directly under the Schottky contact of unterminated and terminated diodes is illustrated in Fig. 2 for m. The applied reverse bias in all cases was 400 V. The field enhancement factor is defined as the ratio of the maximum field under the cathode corner to the field under the center of the contact at the same depth. The field enhancement factor for unterminated Schottky diodes varies from approximately two for highly doped devices cm to approximately 4 for diodes with a doping level of cm . For diodes with edge termination, the field enhancement factor varies from approximately 1.3 to 1.6 over the same range of doping levels. It is clear from Fig. 2 that the field plate does provide field relief at the Schottky contact periphery. The degree of relief increases from approximately 35% for highly doped devices to approximately 60% for lightly doped devices. This reduction may not be significant in absolute terms but it is sufficient to prevent avalanche breakdown. Besides reduction in the electric field magnitude, the field plate also shifts the location of the high field region away from the Schottky contact periphery. As shown in Fig. 3, the location of the high field region moves into the oxide layer in the presence of a field plate. If the oxide layer is sufficiently thick m , it will completely contain the high field region that exists between the field plate and the semiconductor. It will also prevent the formation of a second region of high field stress in the semiconductor under the overlap corner. If the oxide layer is thin, large electric fields can occur in the oxide even at relatively low voltages. For example, simulation of a Schottky diode with a 100 thick oxide layer below the field plate indicates that at a potential of only 550 V the electric field in the oxide is 8 MV/cm. This field is quite large considering the maximum ideal breakdown strength of an oxide layer is only 8–10 MV/cm. Because the field plate’s corner is quite close to the semiconductor, it strongly influences the electric field, cre- ating a second high field region inside the semiconductor under the corner. However, this region is fully depleted of carriers so impact ionization does not occur in this region. In this case, the device breakdown voltage is determined by oxide failure. For extremely thick oxide layers, the field plate is so far away from the semiconductor that it does not have much influence on the electric field distribution. In this case, there is also not much improvement in breakdown voltage. Hence, the optimum thickness of the field plate oxide is that which 1) will be sufficiently thick that the peak electric field inside the oxide will not exceed the breakdown strength of the oxide; 2) will be sufficiently thin that the field plate can influence the electric field distribution inside the semiconductor and provide sufficient field relief at the corner. In fact, from numerous simulation results on diodes with different epi-layer doping concentrations, an empirical relationship (as shown in Fig. 4) was obtained between the required thickness of the oxide layer and the optimized epi-layer thickness (which is determined by the depletion width at breakdown). Oxide breakdown field values were taken from [12]. Zhang et al. [12] observed that an interface charge density of cm could reduce the breakdown voltage of MOS capacitors. Simulations of Schottky diodes with field plates show a similar reduction in reverse breakdown voltage for values of oxide interface charge density greater than cm . Simulations of unterminated Schottky indicate that the field enhancement factor at the cathode corner depends on the epitaxial layer doping concentration. From this, we presume that the usefulness of a field plate will depend on the carrier concentration in the semiconductor. Fig. 5 shows the breakdown voltages of unterminated and terminated SiC Schottky diodes obtained using ATLAS simulation for various doping concentrations. The field plate increases the reverse breakdown voltage to at least 65% of the theoretical maximum predicted by (1). For highly doped devices, the diode with field plate has a breakdown voltage that is over 80% of the theoretical limit. However, it must be noted that a field plate with 7000 thick oxide does not provide much absolute improvement when the concentration is greater than around cm (Fig. 5). For highly doped materials, the electric fields are so large everywhere because of the narrow depletion layer under the cathode that a field plate cannot provide sufficient relief to improve the breakdown voltage of the terminated device. It may be possible to improve the performance of the field plate by reducing the oxide layer thickness to increase the plate’s effect on the epitaxial layer. However, this leads to very large electric fields inside the oxide layer and an oxide breakdown could occur. Field plate performance is also affected by the field plate overlap . Fig. 6 shows how the breakdown voltage and field enhancement factor varies as a function of overlap. It is clear that increasing the field plate overlap up to a certain limit will raise the breakdown voltage. Beyond that limit, the breakdown voltage becomes almost independent of its overlap. Fig. 6 also shows that for a particular doping concentration, the field enhancement factor decreases progressively from the value for the unterminated diode to with increasing field plate overlap until is approximately equal to the depletion width at breakdown ( m for Na cm doping concentration). Further increases in the overlap do not result in any decrease in the field enhancement factor. This is reasonable considering that the lateral spread of the depletion region is comparable to the depth of the depletion region in the vertical direction. The electric field in the semiconductor is significant only in the depleted regions, so field relief is necessary only in these areas. Extending the field plate into unde- pleted regions where the electric field is small does not result in any significant decrease in field enhancement or increase in breakdown voltage. Hence, for a particular carrier concentration and avalanche breakdown conditions, there is a maximum breakdown voltage that can be achieved with the cathode/field plate combination shown in Fig. 1. The optimum field plate overlap for achieving the maximum breakdown voltage for a given doping concentration is roughly equivalent to the optimized epilayer thickness (which is determined by the depletion overlap at breakdown). III. D ISCUSSION The ATLAS software package has three models for impact ionization: Grant’s model; Selberherr’s model; Crowell-Sze model. All three models depend in some way on the reduced field ...

स्रोत : www.researchgate.net

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Mohammed 5 month ago

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