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| 三、 PN结的特性 |
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（一）PN结的单向导电性 |
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PN结具有单向导电性。外加正向电压时，空间电荷区变窄，流过一个较大的正向电流。外加反向电压时，空间电荷区变宽，流过一个很小的反向饱和电流。 |
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（二）PN结的伏安特性 |
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PN结的伏安特性方程为: |
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① U>0且U >>UT时 |
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即正向电流随正向电压的增大按指数规律迅速增大。 |
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② U<0且│U│>>UT时： |
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即加反向电压时，只流过很小的反向饱和电流。 |
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(三）PN结的反向击穿 |
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反向击穿电压：发生击穿所需的反向电压UBR.
PN结的反向击穿：当加到PN结上的反向电压增大到某个数值时，反向电流急剧增加。
特点：随着反向电流急剧增加，PN结的反向电压值增加很少。
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