2 a silicon pn junction has impurity doping

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Unformatted text preview: nge 200 < T < 400 K. The built- in potential is given by (7.10) as 31 ⎛N N ⎞ ⎛ T ⎞ ⎡ 2 ⋅ 4 ⋅ 10 ⎤ Vbi = kBT ln ⎜ a 2 d ⎟ = 0.0259 ⎜ ln ⎢ ⎝ 300 ⎟ ⎣ (1.8 × 10 6 )2 ⎥ ⎠ ⎝ ni ⎠ ⎦ ⎛T⎞ = 1.157 ⎜ ⎝ 300 ⎟ ⎠ This is shown in the figure below: 2 1.5 Built-In Potential (V) 7.7 1/2 ⎧ 2ε sVbi ⎫ ⎧ 2 ⋅ 11.7 ⋅ 8.854 × 10 −12 ⋅ 0.731 ⎫ Na xn = ⎨ ⎬ =⎨ ⎬ −19 22 ⎩ 1.6 × 10 ⋅ 2 ⋅ 2 × 10 ⎭ ⎩ e Nd (Na + Nd ) ⎭ −6 = 0.154 × 10 m = 0.154 µ m 1 0.5 0 200 250 300 350 400 Temperature (K) 8.2 A silicon pn junction has impurity doping concentrations of Nd = 2 x 1015 cm- 3 and Na = 8 x 1015 cm- 3. Determine the minority carrier concentrations at the edges of the space charge region for (a) Va = 0.45 V, (b) Va = 0.55 V, and (c) Va = - 0.55...
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