| 摘要 |
<p>An avalanche photodiode comprises a substrate (21), a first semiconductor layer (22) provided on the substrate and made of a first group III-V compound semiconductor material doped to a first conductivity type for producing carriers in response to optical radiation incident to the avalanche photodiode, a second semiconductor layer (24, 25, 32) provided on the first semiconductor layer and comprising a second group III-V compound semiconductor material doped to the first conductivity for causing an avalanche multiplication of the carriers, a photoreception region (26) formed within the second semiconductor layer and doped to a second conductivity type for forming a p-n junction at an interface to the second semiconductor layer, and a guard ring (27) formed along a lateral boundary of the photoreception region. The second semiconductor layer comprises a first layer (32), a second layer (24) and a third layer (25) with respective impurity concentration levels such that the impurity concentration level of the first layer is substantially smaller than the impurity concentration level of the second layer and the impurity concentration level of the third layer is substantially smaller than the impurity concentration level of the second layer. The guard ring region is formed such that the guard ring (27) extends at least into the second layer.</p> |
