ee310 quiz3

Consider an NP junction with ND >> NA (meaning doping density is much greater in the N-side than P-side) . Which of the following is true? Most of the depletion layer is on the P-‐side Most of the band-bending is on the P-‐side The electric field peaks at the metallurgical junction point

(All options)

If the current through a PN junction diode is 1 mA, what is the applied voltage, VA? (assume diode saturation current = 1nA and VA is applied on the P-side whereas N-side is grounded) 0.36V 0.5V -0.5V -0.36V

0.36V (use Jd = J0(e^qVa/kt - 1))

Assume that the N-side doping density of a PN Junction diode is twice the doping density in the P-side. If the built in voltage of the diode is 0.9V, which of the following is correct? (Assume potential of the neutral P-side is zero) Potential at metallurgical junction = ?

0.6V (?

What is the built-in voltage of a Si PN junction diode whose N-side doping density = 10^16 cm-3 and P-side doping density = 5x10^15 cm-3. 0.7 0.2 1.2 1.7

0.7 (Vbi formula)

Magnitude of electric field in the PN junction depends on Doping density Temperature Applied voltage

All the options are correct

A PN junction is forward biased if higher voltage is applied on the N-side with respect to the P-side. (T/F)

False

A good diode offers high resistance in forward bias and low resistance in reverse bias (T/F)

False

Built-in potential in a PN junction diode is typically higher than the band gap energy converted to volts (T/F)

False

Resistivity of the depletion region of a PN junction diode is independent of applied voltage. (T/F)

False

The electric field in a PN junction diode is zero under equilibrium.(T/F)

False

Which of the following condition increases the electron-hole recombination in a PN junction diode? Forward bias Reverse bias Equilibrium High carrier mobility

Forward bias

Which of the following is true regarding the diode saturation current? Higher the minority carrier lifetime lower is saturation current It does not depends on minority carrier lifetime Higher the minority carrier lifetime higher is saturation current Higher is the applied voltage more is saturation current

Higher the minority carrier lifetime lower is saturation current

Which of the following is true about the energy barrier that keeps electrons on the N-‐side and holes on the P-‐side of a PN junction? It decreases under forward bias and increases under reverse bias. It increases under forward bias and decreases under reverse bias. It increases under forward bias and increases under reverse bias. It decreases under forward bias and decreases under reverse bias.

It decreases under forward bias and increases under reverse bias. (energy barrier = wdep which decreases when Va > 0)

The space charge in the depletion region of a PN junction is due to: Negative ions in the P-side and positive ions in the N-side Electrons in the P-side and holes in the N-side Electrons in the N-side and holes in the P-side Positive ions in the P-side and negative ions in the N-side

Negative ions in the P-side and positive ions in the N-side

Which of the following is true for the forward biasing of an ideal PN junction diode? P-side is connected to positive voltage and N-side is grounded N-side is connected to positive voltage and P-side is grounded Polarity of voltage connection does not matter, only voltage magnitude decides forward biasing None of the options are correct

P-side is connected to positive voltage and N-side is grounded

If the current through a PN junction diode is 1 mA, which of the following statement is true? (assume diode saturation current = 1nA and no reverse breakdown) Diode is forward biased Diode is reverse biased Diode is at equilibrium P-side doping density is higher than N-side doping density

Diode is forward biased (Jd = J0(e^qv/kt - 1))

Consider a symmetrically doped (NA = ND =10^17 cm-3) PN junction diode. What is the resistivity exactly at the metallurgical junction point if the diode is forward biased with 0.5V. Assume mobility of both electron and hole is 1000 cm2/Vs ? 20 Ω-cm 10 Ω-cm 312 kΩ-cm 3125 Ω-cm

20 Ω-cm (use n(x)p(x) = ni^2*e^qVa/KT) n(x) = p(x)

Consider a symmetrically doped (NA = ND =10^17 cm-3) PN junction diode. What is the resistivity exactly at the metallurgical junction point if mobility of both electron and holes is 100 cm2/Vs ?

312.5kOhm (n(x)p(x) = ni^2) n(x) = p(x) = 10^10

Which of the following diode parameter decides the color from an LED ? Band gap of the diode material Applied voltage across the diode Doping in the N and P region Minority carrier lifetime in the diode

Band gap of the diode material

Which of the following is true regarding the capacitance of an PN junction diode Capacitance of the PN junction diode is lower under forward bias compared to reverse bias Capacitance of the PN junction diode is higher under forward bias compared to reverse bias Capacitance of the PN junction diode is independent of applied voltage Capacitance of the PN junction diode depends on the minority carrier lifetime

Capacitance of the PN junction diode is higher under forward bias compared to reverse bias

If N-side doping density of a PN Junction diode is twice the doping density in the P-side, which of the following is true? The maximum resistivity point is on P-side Depletion layer width in the N-side is double than that of in P-side Maximum electric field point is on N-side Maximum electric field point is on P-side

The maximum resistivity point is on P-side (inverse)

A solar cell will produce more photo current in reverse bias than forward bias. (T/F)

True

An LED will produce more light when forward biased compared to reverse biased.(T/F)

True

Built-in voltage of a PN junction diode decreases with higher temperature.(T/F)

True

In a PN junction diode, depletion region has higher resistivity than the neutral region. (T/F)

True

Depletion width (Wdep) of a PN junction diode under equilibrium is 1 micrometer. Which of the following statement is true? Wdep = 2 micrometer under reverse bias Wdep = 2 micrometer under forward bias Wdep = 0.5 micrometer under reverse bias Wdep = 1 micrometer under forward bias

Wdep = 2 micrometer under reverse bias

Assume that the N-side doping density of a PN Junction diode is twice the doping density in the P-side. If the total depletion width = 300 nm, which of the following is correct? (Wn = depletion width in N-side and Wp = depletion width in P-side) Wn =100 nm and Wp = 200nm Wn =150 nm and Wp = 150nm Wn =200 nm and Wp = 100nm Wn =100 nm and Wp = 100nm

Wn =100 nm and Wp = 200nm (inverse relation)

Which of the following correctly describes the effects of temperature on a PN junction diode? Higher the temperature lower is the built-in voltage Higher the temperature lower is the built-in electric field Higher the temperature larger is diode saturation current

all options