Paramaters from problem 1 are as follows: C-Si solar cell, N A =10 17 cm -3 ,N D

Question

Paramaters from problem 1 are as follows:

C-Si solar cell, NA=1017cm-3 ,ND=1019cm-3,up=100cm2/Vs, un=1000cm2/Vs, Lp=10um, Ln=500um, T=293K, VT=25mV, ni=1x1010

3. For the same cell parameters as listed in Problem 1: a. (5 pts) Calculate the built-in voltage VBI. b. (5 pts) Calculate the width of the space-charge region within the p-type base (use x 12 assuming an operating 10 a permittivity of 11.780 with 8.85 voltage of 0.5V. c. (5 pts) The absorption coefficient for c-Si at a wavelength of 600nm is a 4174 cm 1. What fraction of 600nm light (near peak of AM1.5G spectrum is absorbed directly in the space charge region? d. (5 pts) What happens to the 600nm light not absorbed in the space-charge region? e. (5 pts) The absorption coefficient for c-Si at a wavelength of 1100nm is a 3.5 cm 1. What fraction of 1100nm light (near the c-Si bandgap of 1110nm) is absorbed directly in the space charge region? f. (5pts) What happens to the 1100nm light not absorbed in the space-charge region?

Explanation / Answer

1a) built-in poteential Vbi= KT/q(NdNa)/ni^2

we can replace kt/q with Vt then Vbi=Vt(NdNa)/ni^2 , using values we get Vbi= 25ln(10^19*10^17/(10^10)^2)

or Vbi= 921.03mv=.921V

b)The width of space -charge region =-(qNa/)*lp=-(1.602*10^-19*10^17/11.7*8.85*10^-12)*10*10^-5 =.015*10^6m

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