Light-sensing apparatus and light-sensing method thereof

A photo-detecting apparatus, comprising:

• a semiconductor substrate;
• one or more pixels supported by the semiconductor substrate, wherein each of the one or more pixels comprises:
• a germanium-based light absorption material configured to absorb an optical signal having a wavelength greater than 800 nm;
• a first metal line electrically coupled to the germanium-based light absorption material;
• a second metal line electrically coupled to the germanium-based light absorption material;
• a third metal line electrically coupled to the germanium-based light absorption material;
• a fourth metal line electrically coupled to the germanium-based light absorption material;
• a first region doped with a first type of dopant and electrically coupled to the first metal line;
• a second region doped with a second type of dopant, wherein the first metal line is configured to control an amount of a first type of photo-generated carriers generated inside the germanium-based light absorption material to be collected by the second region, and wherein the second type of dopant is different from the first type of dopant;
• a third region doped with the first type of dopant and electrically coupled to the third metal line;
• and
• a fourth region doped with the second type of dopant, wherein the third metal line is configured to control an amount of the first type of photo-generated carriers generated inside the germanium-based light absorption material to be collected by the fourth region,
• wherein a depth of the first region extending from a first surface of the germanium-based light absorption material is deeper than a depth of the second region extending from the first surface of the germanium-based light absorption material.