Q4. A laser beam striking a uniformly doped p-type bar of silicon maintained at room temperature causes a steady state excess of An, 10"/ cm³ electrons at x = 0. Note that the laser-induced photo-generation only occurs at x = 0. As pictured below, the bar extends from x = -L to x =+L and An,(-L) An, (L) = 0. NA=1016/ cm³ and electric field is zero inside the bar. "1-3 Laser Beam Anp(0) = 10 cm" Anp(-4)=0 士 +L Anp(L)=0 P-type 16 NA = 10 con -3 Sketch the expected general form of An,(x) inside the bar (-L<x< L) under steady state conditions. Use the following step by step solution process: (5+5+10+5 points) (a) Simplify the Minority Carrier Diffusion Equation (MCDE) for this problem. In the region: (1) 0 < x <L and (2)-L<x<0 (b) Specify the initial and boundary conditions, as appropriate for the problem (c) Solve the problem and find the expression of electron concentration as a function of position. Assume, L is very large or infinitely long and electron lifetime = T, and electron diffusion coefficient = D (d) Provide a sketch of electron concentration and explain it in words.