Semiconductor light detection device and method of detecting light of specific wavelength

A semiconductor light detection device, comprising:

• a primary semiconductor light receiving element comprising:
• a primary first conductive layer having a first conductivity type on a surface of a semiconductor substrate;
• a primary second conductive layer having a second conductivity type below the primary first conductive layer;
• a primary third conductive layer having the first conductivity type below the primary second conductive layer;
• and
• configured to output, from the primary third conductive layer, a first photocurrent based on an intensity of an incident light irradiating the primary first conductive layer from above while a first input voltage is applied to the primary first conductive layer;
• a secondary semiconductor light receiving element comprising:
• a secondary first conductive layer having the first conductivity type on the surface of the semiconductor substrate;
• a secondary second conductive layer having the second conductivity type below the secondary first conductive layer;
• a secondary third conductive layer having the first conductivity type below the secondary second conductive layer;
• and
• configured to output, from the secondary third conductive layer, a second photocurrent based on the intensity of incident light irradiating the secondary first conductive layer from above while a second input voltage is applied to the secondary first conductive layer;
• and
• a semiconductor light detection circuit comprising:
• a first current-voltage conversion circuit configured to output a first conversion voltage based on the first photocurrent;
• a second current-voltage conversion circuit configured to output a second conversion voltage based on the second photocurrent;
• and
• a differential amplification circuit configured to output a voltage that is based on a difference between the first conversion voltage and the second conversion voltage.

A method of detecting light of a specific wavelength, comprising:

• detecting a first photocurrent based on an intensity of an incident light irradiating a first conductive layer of a semiconductor light receiving element from above, being output from a third conductive layer of the semiconductor light receiving element while a first input voltage is applied to the first conductive layer, the semiconductor light receiving element including the first conductive layer having a first conductivity type on a surface of a semiconductor substrate, a second conductive layer having a second conductivity type below the first conductive layer, and the third conductive layer having the first conductivity type below the second conductive layer;
• detecting a second photocurrent based on the intensity of the incident light being output from the third conductive layer while a second input voltage is applied to the first conductive layer;
• and
• supplying an output voltage based on a current difference between the first photocurrent and the second photocurrent.

A method of detecting light of a specific wavelength, comprising:

• detecting a first photocurrent based on an intensity of an incident light irradiating a primary first conductive layer of a primary semiconductor light receiving element from above, being output from a primary third conductive layer of the primary semiconductor light receiving element while a first input voltage is applied to the primary first conductive layer, the primary semiconductor light receiving element including the primary first conductive layer having a first conductivity type on a surface of a semiconductor substrate, a primary second conductive layer having a second conductivity type below the primary first conductive layer, and the primary third conductive layer having the first conductivity type below the primary second conductive layer;
• detecting a second photocurrent based on the intensity of the incident light irradiating a secondary first conductive layer of a secondary semiconductor light receiving element from above, being output from a secondary third conductive layer of the secondary semiconductor light receiving element while a second input voltage is applied to the secondary first conductive layer, the secondary semiconductor light receiving element including the secondary first conductive layer having the first conductivity type on the surface of the semiconductor substrate, a secondary second conductive layer having the second conductivity type below the secondary first conductive layer, and the secondary third conductive layer having the first conductivity type below the secondary second conductive layer;
• converting the first photocurrent into a first conversion voltage based on the first photocurrent with a first current-voltage conversion circuit;
• converting the second photocurrent into a second conversion voltage based on the second photocurrent with a second current-voltage conversion circuit;
• and
• supplying, from a differential amplification circuit, a voltage based on a difference between the first conversion voltage and the second conversion voltage.