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The doping concentrations on the p-side and n-side of a silicon diode are 1 × 10¹⁶ cm⁻³ and 1 × 10¹⁷ cm⁻³, respectively. A forward bias of 0.3 V is applied to the diode. At T = 300 K, the intrinsic carrier concentration of silicon n_i = 1.5 × 10¹⁰ cm⁻³ and kT/q = 26 mV. The electron concentration at the edge of the depletion region on the p-side is

1. 2.3 × 10¹⁰ cm⁻³
2. 1 × 10¹⁰ cm⁻³
3. 1 × 10¹⁷ cm⁻³
4. 2.25 × 10¹⁶ cm⁻³

Correct answer: 2.3 × 10¹⁰ cm⁻³

Solution

The electron concentration at the edge of the depletion region on the p-side can be calculated using the formula that accounts for the equilibrium condition and the applied forward bias. Given the doping concentrations and the intrinsic carrier concentration, the forward bias reduces the barrier, allowing more electrons to populate the edge of the depletion region, resulting in the calculated value of approximately 2.3 × 10¹⁰ cm⁻³.

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