Ge—Si avalanche photodiode with silicon carrier-energy-relaxation layer and edge electric field buffer region

摘要

Various embodiments of a germanium-on-silicon (Ge—Si) avalanche photodiode are provided. In one aspect, the Ge—Si avalanche photodiode utilizes a silicon carrier-energy-relaxation layer to reduce the energy of holes drifting into absorption layer where the absorption material has lower ionization threshold, thereby suppressing multiplication noise and increasing the gain-bandwidth product of the avalanche photodiode.

主权项

1. An avalanche photodiode comprising:
a substrate; a bottom contact layer including a first semiconductor material disposed on the substrate and doped to exhibit a first conductive type; a multiplication layer including the first semiconductor material 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 above the intrinsic region; andan edge electric field (E-field) buffer region disposed next to an outer periphery of the guard-ring region and unintentionally-doped or lightly-doped to function as a field-ramping region; a carrier-energy-relaxation layer of the first semiconductor material and disposed on the multiplication layer, the carrier-energy-relaxation 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 carrier-energy-relaxation 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, wherein the first semiconductor material comprises silicon, and wherein the second semiconductor material comprises germanium.