| 摘要 |
PURPOSE:To arbitrarily select a breakdown voltage by absorbing a surge current by a punch-through generated when a depletion layer generated by a reverse bias to a P-N junction diode arrives at the third region. CONSTITUTION:When a reverse bias is applied to a P-N junction diode which forms the first semiconductor region 1 and the second semiconductor region 2, a depletion layer generated at the junction is extended to the region 1, and also extended simultaneously toward the third region 3. The depletion layer is continuously extended in response to the magnitude of the applied voltage, and when it arrives at the region 3 soon, a punch-through occurs between the regions 1 and 3. A surge current is absorbed through a current path, and the voltage across the element is clamped to the prescribed value. Accordingly, the punch-through voltage between the regions 1 and 3 and hence the breakdown voltage as a surge absorber can be arbitrarily altered and controlled according to what degree of the effective thickness Dt of the intermediate region 2 is set. |
