Interview Questions.

Question 1. What Is Fermi Level?

Answer :

The most energy that an electron in a steel has on the absolute 0 temperature is known as the Fermi level of power.

Question 2. What Is The Basis For Classifying A Material As A Conductor, Semiconductor, Or A Dielectric? Define What Is The Conductivity Of Perfect Dielectric?

Answer :

Conductors possess high conductivity while the feature belongings of insulating substances (or dielectrics) is negative conductivity. Semiconductors occupy an intermediate role among conductors and insulators. Though there may be no rigid line separating the conductors from semiconductors and semiconductors from insulators, but still consistent with resistivity the materials of resistivity of the order from 10-8 to ten-three , 10-13 to 106 and 106 to 1018 ohm-meters can be labeled as conductors, semiconductors and dielectrics respectively.

Another category is based totally on temperature coefficient of resistivity. Metals have wonderful temperature coefficient of resistivity. Semiconductors have small poor temperature coefficient of resistivity and insulators have massive terrible temperature coefficient of resistivity.

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Question 3. Differentiate Semiconductors, Conductors And Insulators On The Basis Of Band Gap?

Answer :

The distinction among conductors, insulators and semiconductors is basically worried with the relative width of the forbidden energy gaps of their energy band systems. There is a extensive forbidden gap (more than 5eV) for insulators, narrow forbidden hole (about 1eV) in case of semiconductors and no forbidden hole in case of conductors.

Question 4. Define What Is The Importance Of Valence Shell And Valence Electrons?

Answer :

The outermost shell of an atom is referred to as valence shell and the electrons in this shell are known as valence electrons. Formation of strength bands occur owing to overlapping of power tiers of these valence electrons in valence shells. With the lower in interatomic distance among the atoms in a crystal, the power tiers of electrons in outermost shells of atoms overlap to shape energy bands.

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Question 5. What Is The Forbidden Energy Gap? How Does It Occur? Define What Is Its Magnitude For Ge And Si?

Answer :

The power hole between the valence band and conduction band is called forbidden electricity gap. It is a place in which no electron can stay as there's no allowed energy state. Magnitude of forbidden power gap in germanium and silicon is zero.Seventy two eV and 1.12 eV respectively at 300 K and zero.785 eV and 1.21 eV respectively at absolute zero temperature.

Electronic Circuits Interview Questions
Question 6. Is A Hole A Fundamental Particle In An Atom?

Answer :

Hole isn't a essential particle in an atom. Holes may be notion of as wonderful debris, and as such they flow thru an electric powered field in a route opposite to that of electrons.

Question 7. Define A Hole In A Semiconductor?

Answer :

When power is provided to a semiconductor a valence electron is lifted to a higher strength degree. The departing electron leaves a vacancy inside the valence band. The emptiness is known as a hole. Thus, a emptiness left within the valence band due to lifting of an electron from the valence band to conduction band is known as a hollow.

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Question 8. Define What Is Whole Current?

Answer :

The motion of the hole (positively charged emptiness within the valence band) from effective terminal of the supply to terrible terminal via semiconductor constitutes hole contemporary.

Question 9. Define What Is Intrinsic Semiconductor?

Answer :

An intrinsic semiconductor is one which is made of the semiconductor material in the extraordinarily pure form (impurity content material not exceeding one component in a hundred million components of semiconductors).

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Question 10. Why Silicon And Germanium Are The Two Widely Used Semiconductor Materials?

Answer :

Because the electricity required to release an electron from their valence band (i.E. To interrupt their covalent bonds) may be very small (1.12eV for Si and 0.72eV for Ge).

Question eleven. Which Of The Two Semiconductor Materials Si Or Ge Has Larger Conductivity At Room Temperature? Why?

Answer :

Since electricity required in moving electrons from valence band to conduction band is greater in case of Si than that in case of germanium, the conductivity of Ge will be extra than that of Si at room temperature.

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Question 12. Why Does A Pure Semiconductor Behave Like An Insulator At Absolute Zero Temperature?

Answer :

For a natural semiconductor at a temperature of absolute zero (-273.15oC)the valence band is normally complete and there are may be no electron within the conduction band and it's miles difficult to provide additional electricity required for lifting electron from valence band to conduction band by using making use of electric powered field. Hence the conductivity of a pure semiconductor at absolute zero temperature is zero and it behaves like an insulator.

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Question 13. Define What Is The Main Factor For Controlling The Thermal Generation And Recombination?

Answer :

Temperature, due to the fact with the boom within the temperature, concentrations of unfastened electrons and holes boom and the price of recombination is proportional to the made of concentration of unfastened electrons and holes and additionally the charge of manufacturing of electron-hole pairs (thermal generation) increases with the rise in temperature.

Question 14. Define Mean Life Of A Carrier?

Answer :

The amount of time between the introduction and disappearance of a free electron is called the existence time. It varies from some nanoseconds to numerous microseconds relying how best the crystal is and other factors.

Question 15. In Which Bands Do The Movement Of Electrons And Holes Take Place?

Answer :

Free electrons pass in valence band at the same time as holes in valence band.

Analogue electronics Interview Questions
Question 16. Define What Is The Mechanism By Which Conduction Takes Place Inside The Semiconductor?

Answer :

Conduction takes place in any given cloth whilst an applied electric subject causes electrons to move in a desired path within the material. This can be because of one or each of  procedures, electron movement and complete transfer. In case of former method, free electrons within the conduction band flow beneath the impact of the implemented electric discipline. Hole transfer includes electrons which can be nonetheless connected to the atoms i.E. Those in valence band.

Question 17. Define What Do You Mean By Drift Velocity And Mobility Of A Free Electron?

Answer :

The average velocity of an electron is called glide pace whereas mobility of an electron is defined because the drift pace in step with unit electric subject.

Semiconductor Interview Questions
Question 18. Define Mobility Of A Carrier. Show That The Mobility Constant Of Electron Is Larger Than That Of A Hole?

Answer :

Mobility is described because the average particle glide pace per unit electric powered subject.

The mobility of electrons is greater than that of holes because the possibility of an electron having the power required to transport to an empty country n the conduction band is tons more than the possibility of an electron having the energy required to move to the empty nation in valence band. The mobility of electron is ready double that of a hollow.

Electronic Circuits Interview Questions
Question 19. Define Diffusion Current In A Semiconductor?

Answer :

The diffusion of rate providers is a result of a gradient of provider concentration (i.E., the distinction of provider attention from one vicinity to every other). In this example concentrations of price carriers (both electrons or holes) have a tendency to distribute themselves uniformly throughout the semiconductor crystal. This movement continues till all companies are flippantly distributed for the duration of the fabric. This type of movement of price providers is referred to as diffusion present day.

Question 20. Define Drift Current In A Semiconductor?

Answer :

The steady drift of electrons in one direction resulting from carried out electric area constitutes an electric present day, called the drift modern.

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Question 21. Define What Happens To The Conductivity Of Semiconductor With The Rise In Temperature? Compare With The Conductivity Of Metals?

Answer :

With the increase in temperature, the awareness of charge providers will increase resulting in growth in conductivity of semiconductors. The conductivity of metal decreases with the increase in temperature.

Question 22. Why Temperature Coefficient Of Resistance Of A Semiconductor Is Negative?

Answer :

With the boom in temperature, the attention of rate vendors (electrons and holes) increases. As extra fee providers are made to be had, the conductivity of a pure semiconductor increases i.E. Resistivity of a pure semiconductor decreases with the rise in temperature i.E. Semiconductors have bad temperature coefficient of resistance.

Question 23. Define What Is Meant By Fermi Level In Semiconductor? Where Does The Fermi Level Lie In An Intrinsic Semiconductor?

Answer :

Fermi level in a semiconductor may be described because the most energy that an electron in a semiconductor has at absolute zero temperature. In an intrinsic semiconductor, the Fermi degree lies midway among the conduction and valence bands.

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Question 24. Differentiate Between Intrinsic Semiconductors And Intrinsic Semiconductors?

Answer :

An intrinsic semiconductor is one which is manufactured from the semiconductor fabric in its extraordinarily pure form.

When a small amount of impurity is delivered to a natural semiconductor crystal at some stage in the crystal increase that allows you to boom its conductivity, the ensuing crystal is referred to as extrinsic semiconductor.

Digital Electronics Interview Questions
Question 25. Why Doping Is Done In Semiconductors?

Answer :

Intrinsic (or natural) semiconductor by using itself is of little significance as it has little contemporary conduction functionality at regular room temperature. However, if very small amount of impurity (of the order of one atom in line with million atoms of pure semiconductor) is brought to it inside the technique of crystallization, the electric conductivity is accelerated often.

Question 26. Describe The Difference Between P-kind And N-kind Semiconductor Materials?

Answer :

When a small quantity of trivalent impurity (which includes boron, gallium, indium or aluminium) is added to a natural semiconductor crystal all through crystal growth, the ensuing crystal is called a P-type semiconductor.

When a small quantity of pentavalent impurity (which includes arsenic, antimony, bismuth or phosphorus) is added to a pure semiconductor crystal throughout crystal growth, the resulting crystal is known as the N-kind semiconductor.

Diode Interview Questions
Question 27. Define What Do You Mean By Donor And Accept Or Impurities?

Answer :

Donor impurities (inclusive of arsenic, antimony, bismuth or phosphorous) while introduced to a natural semiconductor lattice, shape N-kind extrinsic semiconductor. The pentavalent impurities are referred to as donor impurities as such impurities donate electrons to the lattice.

Acceptor impurities (along with boron, gallium, indium or aluminium) when added to a semiconductor lattice form P-type extrinsic semiconductor. The trivalent impurities are known as acceptor impurities because such impurities accept electrons from the lattice.

Electrical Engineering Interview Questions
Question 28. Explain The Term Doping And Its Need?

Answer :

The electrical conductivity of intrinsic semiconductor, which has little current engaging in functionality at room temperature and so is of little use, may be elevated normally with the aid of adding very small quantity of impurity (of the order of one atom in keeping with million atoms of pure semiconductor) to it in the system of crystallization. This procedure is referred to as doping.

Question 29. Define What Is The Effect Of Temperature On Extrinsic Semiconductor?

Answer :

With the increase in temperature of an extrinsic semiconductor, the number of thermally generated vendors is expanded ensuing in increase in awareness of minority carriers. At temperature exceeding critical temperature the extrinsic semiconductor behaves like an intrinsic semiconductor but with better conductivity.

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Question 30. Define What Are The Charge Carriers In P-kind And N-type Semiconductors?

Answer :

Fee electrons in n-kind semiconductors and holes in p-kind semiconductors are the fee vendors.

Question 31. For The Same Order Of Doping, Why Does N-type Semiconductor Exhibit Larger Conductivity Than P-kind Semiconductor?

Answer :

Since the mobility of electrons is better than that of holes, for equal level of doping, n-kind semiconductor well-knownshows larger conductivity.

Question 32. What Is The Ratio Of Majority And Minority Carriers In Intrinsic And Extrinsic Semiconductors?

Answer :

For intrinsic semiconductor the ratio of majority and minority companies is Unity.

For extrinsic semiconductor the ratio of majority and minority providers is Very huge.

VLSI Design Interview Questions
Question 33. Define What Is A P-n Junction?

Answer :

The touch floor among the layers of p-kind and n-kind semiconductor pieces positioned collectively so one can form a p-n junction is known as the p-n junction.

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Question 34. How Do The Transition Region Width And Contact Potential Across A P-n Junction Vary With The Applied Bias Voltage?

Answer :

When the p-n junction is ahead biased, the transition vicinity width is reduced and the contact potential is likewise decreased with the increase in implemented bias voltage.

When the p-n junction is reverse biased, the transition is widened, and the touch ability is increased and with the increase in implemented bias voltage.

Question 35. Which Type Of Charges Present On The Two Opposite Faces Of The Junction?

Answer :

Positive fee on n-aspect and bad fee on p-facet of the junction.

Question 36. Define What Types Of Carriers Are Present In Space Charge Region?

Answer :

No cell carrier is present within the area rate location.

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Question 37. Why Is Space Region Called The Depletion Region?

Answer :

The place across the junction is completely ionized on formation of p-n junction. As a end result, there aren't any free electrons on the n-aspect nor the holes at the p-side. Since the vicinity across the junction is depleted of cellular costs, it is referred to as the depletion area.

Question 38. Why An Electric Field Is Produced In A Depletion Region Of A P-n Junction?

Answer :

The separation of nice and terrible area price densities in a p-n junction effects in an electric subject.

Question 39. Define What Is Space Charge Width?

Answer :

The area price place extends into the n and p-regions from the metallurgical junction. The distance is referred to as the space fee width.

Question 40. The Electric Field In The Space Charge Region Decreases With Forward Bias And Increases With Reverse Bias. Why?

Answer :

Because carried out electric powered subject opposes built-in subject.

Semiconductor Interview Questions
Question forty one. Define Cut-in Voltage Of A P-n Junction Diode?

Answer :

The ahead voltage, at which the contemporary via the p-n junction begins growing unexpectedly, is referred to as the cut-in voltage.

Question 42. Define What Do You Understand By Reverse Saturation Current Of A Diode?

Answer :

Reverse saturation cutting-edge of a diode is due to minority vendors and is caused while the diode is opposite biased. Only a very small voltage is required to direct all minority carriers across the junction, and whilst all minority providers are flowing throughout, further boom in bias voltage will now not cause boom in modern-day. This present day is known as reverse saturation modern.

Digital Logic Design Interview Questions
Question forty three. Define What Is The Effect Of Temperature On The Reverse Current Of A P-n Junction?

Answer :

Reverse modern of a p-n junction increases with the boom in junction temperature.

Question forty four. Why Is Silicon Preferred To Germanium In The Manufacturing Of Semiconductor Devices?

Answer :

Silicon desired to germanium within the production of semiconductor gadgets because such gadgets have higher peak inverse voltage and present day rankings and wider temperature range than germanium ones.

Question 45. Define Peak Inverse Voltage?

Answer :

Peak inverse voltage is the maximum voltage that can be applied to the p-n junction with out adverse the junction. If the opposite voltage across the junction exceeds its height inverse voltage(PIV), the junction can also get destroyed as a result of immoderate warmth.

Question 46. Define Breakdown Voltage?

Answer :

Breakdown voltage is described because the opposite voltage at which p-n junction breaks down with unexpected upward push with reverse present day.

Question 47. Define The Limitations In The Operation Conditions Of A P-n Junction?

Answer :

Every p-n junction has proscribing values of:

Maximum forward present day
Peak inverse voltage (PIV)
Maximum strength score
The p-n junction offers exceptional overall performance when operated within these proscribing values. The p-n junction diode may additionally get destroyed due to excessive warmth if any of those values are surpassed.