In a semiconductor p-n junction, the doping concentration on the p-side is 10¹⁵ atoms·cm⁻³ and that on the n-side is 10¹⁸ atoms·cm⁻³. Which statement about the depletion-region widths is correct?
Options

Question

In a semiconductor p-n junction, the doping concentration on the p-side is 10¹⁵ atoms·cm⁻³ and that on the n-side is 10¹⁸ atoms·cm⁻³. Which statement about the depletion-region widths is correct?

Options

G1 Physics · Accepted Answer

Charge neutrality in the depletion region requires equal magnitudes of uncovered charge on both sides: N(A)x(p) = N(D)x(n). Here, N(A) = 10¹⁵ cm⁻³, N(D) = 10¹⁸ cm⁻³. Therefore, x(p) ÷ x(n) = N(D) ÷ N(A) = 10¹⁸ ÷ 10¹⁵ = 10³. Thus the depletion region extends much farther into the more lightly doped p-side. Correct option: B.