Interface electric field confinement effect of high-sensitivity lateral Ge/Si avalanche photodiodes

A novel lateral Ge/Si avalanche photodiode without a charge region is investigated herein using device physical simulation. High field is provided by the band-gap barrier and build-in field at the Ge/Si interface in the vertical direction. Modulating the Si mesa thickness (0-0.4 μm) and impurity concentration of the intrinsic Si substrate (1 × 10
¹⁶
-4 × 1016 cm
^-3
) strengthens the electric field confinement in the substrate region and provides a high avalanche multiplication in the Si region. When the Si mesa thickness is 0.3 μm, and the impurity concentration of the Si substrate is 2 × 10
¹⁶
cm
^-3
, the Lateral Avalanche PhotoDiode (LAPD) exhibits a peak gain of 246 under 1.55 μm incident light power of -22.2dBm, which increases with decreasing light intensity.