HIGH-EFFICIENCY BANDWIDTH PRODUCT GERMANIUM PHOTODETECTOR

摘要

A high-efficiency bandwidth product germanium photodetector includes a silicon substrate having an opening-down three-sided groove formed by etching; a metallic reflective mirror layer formed by plating along an internal periphery of the opening-down three-sided groove of the silicon substrate; a light absorbent layer between the metallic reflective mirror layer and a dielectric reflective mirror layer. The light absorbent layer can be p-i-n type or other types. By the use of the critical coupling of resonant cavity, all the incident lights can be completely obstructed in the cavity between the metallic reflective mirror layer and the dielectric reflective mirror layer to reach a critical coupling which means 100% absorption efficiency can be achieved without light leakage. Thus on the basis of the critical coupling, the trade-off between bandwidth and efficiency can be broken through to reach high responsivity and high bandwidth up to 50 GHz by decreasing the germanium layer thickness without sacrificing the light-switch-to-electro absorption efficiency.

主权项

1. A high-efficiency bandwidth product germanium photodetector comprising:
a silicon substrate, having an opening-down three-sided groove; a metallic reflective mirror layer; disposed along an internal periphery of the opening-down three-sided groove of the silicon substrate, and therefore having the opening-down three-sided structure conform to the opening-down three-sided groove; a light absorbent layer, disposed on the metallic reflective mirror layer and having a pin structure which includes a p-type amorphous silicon layer (a-Si), an i-type germanium layer and an n-type epitaxial silicon layer (Epi-Si); and a dielectric reflective mirror layer, disposed on the absorbent layer, wherein with the use of the metal reflective mirror layer, a resonator structure which allows the light to reflect several times is formed; wherein the reflectance ratio of the dielectric reflective mirror layer to the metallic reflective mirror layer equals to the remained light intensity ratio in the resonant cavity, and by means of critical coupling of a resonant cavity, all the incident lights are locked in the cavity between the metallic reflective mirror layer 1 and the dielectric reflective mirror layer so as to achieve one hundred percent absorption.