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ECE 874: Physical Electronics

ECE 874: Physical Electronics. Prof. Virginia Ayres Electrical & Computer Engineering Michigan State University ayresv@msu.edu. Lecture 26, 27 Nov 12 Chp. 05: Recombination-Generation Processes. baseline situation. W. Reverse biassed pn junction:. Ideally in depletion region W: p = n = 0

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ECE 874: Physical Electronics

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  1. ECE 874:Physical Electronics Prof. Virginia Ayres Electrical & Computer Engineering Michigan State University ayresv@msu.edu

  2. Lecture 26, 27 Nov 12Chp. 05: Recombination-Generation Processes VM Ayres, ECE874, F12

  3. baseline situation W VM Ayres, ECE874, F12

  4. Reverse biassed pn junction: • Ideally in depletion region W: p = n = 0 • (always do have thermally generated ni/pi but internal field E in W continuously sweeps them out) VM Ayres, ECE874, F12

  5. New stuff in the picture: the effect of light VM Ayres, ECE874, F12

  6. Effect of shining light on reverse biassed pn junction: • In depletion region W: p = n ≠ 0 • In depletion region W: p = n = large • In depletion region W: VM Ayres, ECE874, F12

  7. xpp VM Ayres, ECE874, F12

  8. VM Ayres, ECE874, F12

  9. VM Ayres, ECE874, F12

  10. VM Ayres, ECE874, F12

  11. Lecture 26, 27 Nov 12Chp. 06: Currents VM Ayres, ECE874, F12

  12. General assuming capture/emission coefficients don’t change much from equilibrium values: Steady state: (5.24) Equilibrium: 0 VM Ayres, ECE874, F12

  13. Now include the ordinary mechanisms that can change n and p:drift currents and diffusion currents And anything else! drift diffusion VM Ayres, ECE874, F12

  14. Now include the ordinary mechanisms that can change n and p:drift currents and diffusion currents And anything else! VM Ayres, ECE874, F12

  15. Now include the ordinary mechanisms that can change n and p:drift currents and diffusion currents And anything else! 6.1: review of drift 6.2: review of diffusion 6.3: list of equations for dn/dt, dp/dt and J’s – no new material VM Ayres, ECE874, F12

  16. Hw06 Prs. 6.3 and 6.4: Diffusion: diff diff A diffusion current happens anytime you have a spatial variation in the concentrations of n or p VM Ayres, ECE874, F12

  17. Example problem: from Pr. 6.4: Put a red box around any region where n-type ness changes: dn/dx Put a blue box around any region where p-type ness changes: dp/dx -L -L/2 0 L/2 L VM Ayres, ECE874, F12

  18. Example problem: from Pr. 6.4: Put a red box around any region where n-type ness changes: dn/dx Put a blue box around any region where p-type ness changes: dp/dx -L -L/2 0 L/2 L VM Ayres, ECE874, F12

  19. Example problem: from Pr. 6.4: hole VM Ayres, ECE874, F12 -L -L/2 0 L/2 L

  20. VM Ayres, ECE874, F12

  21. VM Ayres, ECE874, F12

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