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Problem 3 = Consider a bar of silicon of length L 1 mm which is uniformly doped with 5 × 1016 cm-3 phosphorus atoms. At both ends of the bar, there are metal contacts at which all of the excess generated carriers recombine (An = Ap = 0). Light with a generation rate of G = 5×1021 cm−³ s−1 is shined uniformly on the bar at room temperature. The electron and hole lifetimes are Tr = =Tp= 0.1 μs. The cross-sectional area of the bar is A = 1 mm². Assume steady-state conditions. Ap = 0 ww ww W wx ww Ap=0 phosphorus-doped Si + 0 x+ L (a) Calculate Lp, the hole diffusion length in the Silicon bar. (b) Qualitatively draw the energy band diagram of Silicon bar under illumination. Label Ec, Ev, Ei, and the Fermi or quasi-Fermi Levels. (c) Estimate the value of p, the hole concentration, in the middle of the bar at x = L/2. (d) On a single plot, qualitatively sketch the electron and hole concentrations in the Silicon bar under illumination. (e) The light illumination is suddenly turned off. Qualitatively sketch the resistance of the bar as a function of time.

Problem 3 = Consider a bar of silicon of length L 1 mm which is uniformly doped with 5 × 1016 cm-3 phosphorus atoms. At both ends of the bar, there are metal contacts at which all of the excess generated carriers recombine (An = Ap = 0). Light with a generation rate of G = 5×1021 cm−³ s−1 is shined uniformly on the bar at room temperature. The electron and hole lifetimes are Tr = =Tp= 0.1 μs. The cross-sectional area of the bar is A = 1 mm². Assume steady-state conditions. Ap = 0 ww ww W wx ww Ap=0 phosphorus-doped Si + 0 x+ L (a) Calculate Lp, the hole diffusion length in the Silicon bar. (b) Qualitatively draw the energy band diagram of Silicon bar under illumination. Label Ec, Ev, Ei, and the Fermi or quasi-Fermi Levels. (c) Estimate the value of p, the hole concentration, in the middle of the bar at x = L/2. (d) On a single plot, qualitatively sketch the electron and hole concentrations in the Silicon bar under illumination. (e) The light illumination is suddenly turned off. Qualitatively sketch the resistance of the bar as a function of time.

Delmar's Standard Textbook Of Electricity
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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Problem 3 = Consider a bar of silicon of length L 1 mm which is uniformly doped with 5 × 1016 cm-3 phosphorus atoms. At both ends of the bar, there are metal contacts at which all of the excess generated carriers recombine (An = Ap = 0). Light with a generation rate of G = 5×1021 cm−³ s−1 is shined uniformly on the bar at room temperature. The electron and hole lifetimes are Tr = =Tp= 0.1 μs. The cross-sectional area of the bar is A = 1 mm². Assume steady-state conditions. Ap = 0 ww ww W wx ww Ap=0 phosphorus-doped Si + 0 x+ L (a) Calculate Lp, the hole diffusion length in the Silicon bar. (b) Qualitatively draw the energy band diagram of Silicon bar under illumination. Label Ec, Ev, Ei, and the Fermi or quasi-Fermi Levels. (c) Estimate the value of p, the hole concentration, in the middle of the bar at x = L/2. (d) On a single plot, qualitatively sketch the electron and hole concentrations in the Silicon bar under illumination. (e) The light illumination is suddenly turned off. Qualitatively sketch the resistance of the bar as a function of time.
Transcribed Image Text:Problem 3 = Consider a bar of silicon of length L 1 mm which is uniformly doped with 5 × 1016 cm-3 phosphorus atoms. At both ends of the bar, there are metal contacts at which all of the excess generated carriers recombine (An = Ap = 0). Light with a generation rate of G = 5×1021 cm−³ s−1 is shined uniformly on the bar at room temperature. The electron and hole lifetimes are Tr = =Tp= 0.1 μs. The cross-sectional area of the bar is A = 1 mm². Assume steady-state conditions. Ap = 0 ww ww W wx ww Ap=0 phosphorus-doped Si + 0 x+ L (a) Calculate Lp, the hole diffusion length in the Silicon bar. (b) Qualitatively draw the energy band diagram of Silicon bar under illumination. Label Ec, Ev, Ei, and the Fermi or quasi-Fermi Levels. (c) Estimate the value of p, the hole concentration, in the middle of the bar at x = L/2. (d) On a single plot, qualitatively sketch the electron and hole concentrations in the Silicon bar under illumination. (e) The light illumination is suddenly turned off. Qualitatively sketch the resistance of the bar as a function of time.
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