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Holes are injected into n-type Ge so that the at the surface of the semiconductor hole concentration is 1014/cm3. If diffusion constant of a hole in Ge is 49cm2/sec and minority carrier lifetime is τp = 10-3 sec. Then the hole concentration Δp at a distance of 4mm from the surface is ______1014/cm3
  • a)
    0.12
  • b)
    0.10
  • c)
    0.16
  • d)
    None of the above
Correct answer is option 'C'. Can you explain this answer?
Verified Answer
Holes are injected into n-type Ge so that the at the surface of the se...
 
= 1.6 × 1013/cm3
= 0.16 × 1014/cm3
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Most Upvoted Answer
Holes are injected into n-type Ge so that the at the surface of the se...
To find the hole diffusion length, we need to first calculate the minority carrier diffusion coefficient (D) using the Einstein relationship:

D = k*T*q*μ

where D is the diffusion coefficient, k is Boltzmann's constant (1.38x10^-23 J/K), T is the temperature in Kelvin, q is the elementary charge (1.6x10^-19 C), and μ is the hole mobility.

Assuming room temperature (T = 300 K) and a typical hole mobility for Ge (μ = 0.39 m^2/Vs), we can calculate the diffusion coefficient:

D = (1.38x10^-23 J/K) * (300 K) * (1.6x10^-19 C) * (0.39 m^2/Vs)
≈ 3.24x10^-4 m^2/s

Now, we can calculate the diffusion length (L) using the formula:

L = √(D * τ)

where L is the diffusion length and τ is the minority carrier lifetime.

Given that the hole concentration at the surface is 10^14/cm^3, we convert it to m^3 by multiplying by (10^6 cm/m)^3:

hole concentration = (10^14/cm^3) * (10^6 cm/m)^3
= 10^14 * 10^18 / m^3
= 10^32 / m^3

Since the hole concentration is much higher than the intrinsic carrier concentration, we can assume that the majority carrier concentration is equal to the intrinsic carrier concentration (ni) in Ge, which is approximately 2.4x10^13/cm^3 or 2.4x10^19/m^3.

Now, we can calculate the minority carrier lifetime (τ) using the formula:

τ = (L^2 * ni) / D

τ = [(L^2 * (2.4x10^19/m^3)) / 3.24x10^-4 m^2/s]

Given that the hole concentration at the surface is 10^14/cm^3, we convert it to m^3 by multiplying by (10^6 cm/m)^3:

hole concentration = (10^14/cm^3) * (10^6 cm/m)^3
= 10^14 * 10^18 / m^3
= 10^32 / m^3

Since the hole concentration is much higher than the intrinsic carrier concentration, we can assume that the majority carrier concentration is equal to the intrinsic carrier concentration (ni) in Ge, which is approximately 2.4x10^13/cm^3 or 2.4x10^19/m^3.

Now, we can calculate the minority carrier lifetime (τ) using the formula:

τ = (L^2 * ni) / D

τ = [(L^2 * (2.4x10^19/m^3)) / 3.24x10^-4 m^2/s]

Assuming a typical diffusion length for Ge (L = 10 μm or 10^-5 m), we can calculate the minority carrier lifetime:

τ = [(10^-5 m)^2 * (2.4x10^19/m^3)] / (3.24x10^-4 m^2/s)
=
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Holes are injected into n-type Ge so that the at the surface of the semiconductor hole concentration is 1014/cm3. If diffusion constant of a hole in Ge is 49cm2/sec and minority carrier lifetime is τp= 10-3sec. Then the hole concentration Δp at a distance of 4mm from the surface is ______1014/cm3a)0.12b)0.10c)0.16d)None of the aboveCorrect answer is option 'C'. Can you explain this answer?
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Holes are injected into n-type Ge so that the at the surface of the semiconductor hole concentration is 1014/cm3. If diffusion constant of a hole in Ge is 49cm2/sec and minority carrier lifetime is τp= 10-3sec. Then the hole concentration Δp at a distance of 4mm from the surface is ______1014/cm3a)0.12b)0.10c)0.16d)None of the aboveCorrect answer is option 'C'. Can you explain this answer? for Electronics and Communication Engineering (ECE) 2024 is part of Electronics and Communication Engineering (ECE) preparation. The Question and answers have been prepared according to the Electronics and Communication Engineering (ECE) exam syllabus. Information about Holes are injected into n-type Ge so that the at the surface of the semiconductor hole concentration is 1014/cm3. If diffusion constant of a hole in Ge is 49cm2/sec and minority carrier lifetime is τp= 10-3sec. Then the hole concentration Δp at a distance of 4mm from the surface is ______1014/cm3a)0.12b)0.10c)0.16d)None of the aboveCorrect answer is option 'C'. Can you explain this answer? covers all topics & solutions for Electronics and Communication Engineering (ECE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Holes are injected into n-type Ge so that the at the surface of the semiconductor hole concentration is 1014/cm3. If diffusion constant of a hole in Ge is 49cm2/sec and minority carrier lifetime is τp= 10-3sec. Then the hole concentration Δp at a distance of 4mm from the surface is ______1014/cm3a)0.12b)0.10c)0.16d)None of the aboveCorrect answer is option 'C'. Can you explain this answer?.
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