4. A sample of intrinsic GaN is illuminated with a 10 mW/cm² beam of light at the blue edge of what people can see, λ = 300 nm. The electron lifetime is 2 ps. The electron mobility for intrinsic GaN is about 400 cm²/V's and hole mobility is about 100 cm²/V.s. (GaN intrinsic carrier density is 1.9 × 10-10 cm³) What is the number of photons arriving at the semiconductor surface per sec? (Recall energy power x time.) b. Verify that photons of this energy can be absorbed. c. Assuming energy photon is absorbed and creates an electron-hole pair, and assuming the GaN sample is 1 mm thick, what is the optical generation rate? d. What are the equilibrium electron and hole densities (in the dark)? e. What are the excess carrier concentrations when the light is on? f. What are the recombination rates for electrons and for holes when the light is off? When the light is on? g. What are the steady-state carrier densities n and p? h. How much does the conductivity of this sample change compared with its dark value? i. Suppose the power level is kept the same, but the wavelength of the light is shifted to the red edge of human vision (λ = 700 nm). What is the generation rate now?

4. A sample of intrinsic GaN is illuminated with a 10 mW/cm² beam of light at the blue edge of what people can see, λ = 300 nm. The electron lifetime is 2 ps. The electron mobility for intrinsic GaN is about 400 cm²/V's and hole mobility is about 100 cm²/V.s. (GaN intrinsic carrier density is 1.9 × 10-10 cm³) What is the number of photons arriving at the semiconductor surface per sec? (Recall energy power x time.) b. Verify that photons of this energy can be absorbed. c. Assuming energy photon is absorbed and creates an electron-hole pair, and assuming the GaN sample is 1 mm thick, what is the optical generation rate? d. What are the equilibrium electron and hole densities (in the dark)? e. What are the excess carrier concentrations when the light is on? f. What are the recombination rates for electrons and for holes when the light is off? When the light is on? g. What are the steady-state carrier densities n and p? h. How much does the conductivity of this sample change compared with its dark value? i. Suppose the power level is kept the same, but the wavelength of the light is shifted to the red edge of human vision (λ = 700 nm). What is the generation rate now?

Delmar's Standard Textbook Of Electricity

7th Edition

ISBN:9781337900348

Author:Stephen L. Herman

Publisher:Stephen L. Herman

Chapter1: Atomic Structure

Section: Chapter Questions

Problem 6RQ: How many valence electrons are generally contained in materials used for insulators?

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