| 摘要 |
PURPOSE:To satisfy simultaneously high-speed response and low noise in a semiconductor light receiving element including a hetero-junction by selectively installing a semiconductor layer which has narrow forbidden bandwidth in a semiconductor element. CONSTITUTION:The first semiconductor layer 12 of the first conductive type which constitutes a light absorbing layer, the second semiconductor layer 13 of the first conductive type which has forbidden bandwidth wider than the first semiconductor layer, the third semiconductor layer 14 of the first conductive type which has forbidden bandwidth wider than the second semiconductor layer 13, the fourth semiconductor layer 16 of the second conductive type which constitutes a light receiving part and the fifth semiconductor layer 15 of the first conductive type which is selectively installed under the fourth semiconductor layer 16 within the third semiconductor layer 14 are installed. Consequently, the layer 15, the layer 16 and the multiplying region become wider and the breakdown electric field is weakened whereby ionization ratio of electron and hole becomes greater and low noise can be obtained.
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