A Ge-Si Avalanche Photodiode With Silicon Buffer Layer And Edge Electric Field Buffer Region

An avalanche photodiode comprising:

• a substrate;
• a bottom contact layer including a first semiconductor material and disposed on the substrate, the bottom contact layer doped to exhibit a first conductive type;
• a multiplication layer including the first semiconductor material and disposed on the bottom contact layer, the multiplication layer comprising:
• a bottom region doped to exhibit the first conductive type;
• an intrinsic region unintentionally doped or lightly doped to function as a multiplication region;
• a charge region doped to exhibit a second conductive type and disposed at a center region of a top portion of the multiplication layer above the intrinsic region;
• and
• an edge electric field (E-field) buffer region unintentionally-doped or lightly-doped to function as a field-ramping region;
• is a buffer layer of the first type of semiconductor material and disposed on the multiplication layer, the buffer layer comprising:
• an unintentionally-doped or lightly-doped region configured to function as a buffer to reduce energy of drifting hot carriers;
• and
• a guard-ring region disposed next to an outer periphery of the charge region of the multiplication layer above the intrinsic region, wherein the edge electric field buffer region is disposed next to an outer periphery of the guard-ring region;
• an absorption layer of a second semiconductor material and disposed on the buffer layer;
• a top contact layer disposed on the absorption layer and doped to exhibit the second conductive type;
• and
• an anti-reflection layer disposed on the top contact layer.

An avalanche photodiode comprising:

• a substrate;
• a bottom contact layer including a first semiconductor material and disposed on the substrate, the bottom contact layer doped to exhibit a first conductive type;
• a multiplication layer including the first semiconductor material and disposed on the bottom contact layer, the multiplication layer comprising:
• a bottom region doped to exhibit the first conductive type;
• an intrinsic region unintentionally doped or lightly doped to function as a multiplication region;
• a charge region doped to exhibit a second conductive type and disposed at a center region of a top portion of the multiplication layer above the intrinsic region;
• a guard-ring region disposed next to an outer periphery of the charge region of the multiplication layer and above the intrinsic region;
• and
• an edge electric field (E-field) buffer region disposed next to an outer periphery of the guard-ring region, the edge E-field buffer region unintentionally doped or lightly doped to function as a field-ramping is region;
• an absorption layer of a second semiconductor material and disposed on the multiplication layer;
• a top contact layer disposed on the absorption layer and doped to exhibit the second conductive type;
• and
• an anti-reflection layer disposed on the top contact layer.

An avalanche photodiode comprising:

• to a substrate;
• a bottom contact layer including a first semiconductor material and disposed on the substrate, the bottom contact layer doped to exhibit a first conductive type;
• a multiplication layer including a first semiconductor material and disposed on the bottom contact layer, the multiplication layer comprising:
• a bottom region doped to exhibit a first conductive type;
• an intrinsic region unintentionally doped or lightly doped to function as a multiplication region;
• a charge region doped to exhibit a second conductive type and disposed at a center region of a top portion of the multiplication layer above the intrinsic region;
• and
• a guard-ring region disposed next to an outer periphery of the charge region of the multiplication layer and above the intrinsic region;
• a buffer layer of the first semiconductor material and disposed on the multiplication layer, the buffer layer unintentionally doped or lightly doped to function as a buffer to reduce energy of drifting hot carriers;
• an absorption layer of a second semiconductor material and disposed on the buffer layer;
• a top contact layer disposed on the absorption layer and doped to exhibit a second conductive type;
• and
• an anti-reflection layer disposed on the top contact layer.

An avalanche photodiode comprising:

• a substrate;
• a bottom contact layer including a first semiconductor material and disposed on the substrate, the bottom contact layer doped to exhibit a first conductive type;
• a multiplication layer including the first semiconductor material and disposed on the bottom contact layer, the multiplication layer comprising:
• a bottom region doped to exhibit the first conductive type;
• an intrinsic region unintentionally doped or lightly doped to function as a multiplication region;
• and
• a charge region doped to exhibit a second conductive type and disposed at a center region of a top portion of the multiplication layer above the intrinsic region;
• a buffer layer of the first semiconductor material and disposed on the multiplication layer, the buffer layer comprising:
• an unintentionally-doped or lightly-doped region which functions is as a buffer to reduce energy of drifting hot carriers;
• and
• a guard-ring region disposed next to an outer periphery of the charge region of the multiplication layer above the intrinsic region;
• an absorption layer of a second semiconductor material and disposed on the buffer layer;
• a top contact layer disposed on the absorption layer and doped to exhibit a second conductive type;
• and
• an anti-reflection layer disposed on the top contact layer.