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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
BuiltIn 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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 Fall '14

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