Fabrication process for low cost GaInAsP/InP etched-facet photodetectors

摘要

The optical waveguide entry facet of high-speed, 40 GHz waveguide photodetectors is usually obtained by manual cleaving, which has limited accuracy (± 10 μm) and reduces fabrication yields. In our new fabrication process, the waveguide facet is obtained with Chemically Assisted Ion Beam Etching (CAIBE). Length is therefore precisely controlled by photolithography. The antireflection coating is also deposited collectively on the whole wafer, which further reduces costs. The bandwidth of the photodiodes is 50 GHz, and their optical responsivity is 0.6 A/W at 1.55 μm wavelength. Other techniques, such as Inductively Coupled Plasma Etching (ICP), were also investigated for reducing leakage current.