{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Week7HW Solutions

Find the steady state excess minority carrier

Info icon This preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: his problem. Since this is a steady- state problem, there is no initial condition. At x = L , we expect all of the minority carriers to have recombined, so: Δn ( x = L ) = 0 At the surface, the total number of e- h pairs generation per cm2 per second is GS = GL Δx = 102410−6 = 1018 cm -2s-1 . In steady- state, these must diffuse away at the same rate that they are generated, so − Dn d Δn = GS dx x =0 9c) Solve the problem. Solution: d 2 Δn = 0 solutions is Δn ( x ) = Ax + B dx 2 To satisfy the first boundary condition in 9b): Δn ( L ) = AL + B = 0 . B = − AL Now consider the second: D GS d Δn 1018 − Dn → − n A = GS → A = − =− = −6.4 × 1013 cm -3 −4 dx x=0 L ( Dn L) 7.8 5 × 10 ECE- 606 16 Spring 2013 Mark Lundstrom Δn ( x ) = ( 2/24/2013 ) GS ( L − x ) = 6.4 × 1013 ( L − x ) ( Dn L) 9d) Provide a sketch of the solution, and explain it in words. Concentration increases towards surface, because generation occurs the. Is zero at x = L because of the boundary condition there. Variation is linear with position because there is no recombination. Electron QFL(x) follows from n ( x ) ≈ Δn ( x ) = ni e − ( Fn ( x )− Ei ) / k BT . 10) The sample is in the dark, but the excess carrier concentration at x = 0 is held constant at Δn ( 0 ) = 1012 cm- 3. Find the steady state excess minority carrier concentration and QFL’s vs. position. You may assume that the sample extends to x = +∞ . Make reasonable approximations, and approach the problem as follows. 10a) Simplify the Minority Carrier Diffusion Equation for this problem...
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern