Method for determining wavelengths of light incident on a stacked photodetector structure

A method for determining a wavelength of light incident on a semiconductor device comprising an upper photodiode vertically disposed on a lower photodiode, the method comprising:

• biasing the upper photodiode at a first bias voltage and biasing the lower photodiode at a second bias voltage;
• measuring a first current generated by the upper photodiode and a second current generated by the lower photodiode in response to the light incident on the semiconductor device;
• changing at least one of the first bias voltage and the second bias voltage;
• measuring a modified first current and a modified second current in response to the light incident on the semiconductor device;
• and
• determining the wavelength of the light incident on the semiconductor device in response to the measured first and second currents, the measured modified first and second currents, and a predetermined correspondence between the measured and modified first and second currents as a function of wavelength and bias voltage.

A device for determining a wavelength of light, comprising:

• a semiconductor structure having an upper photodiode vertically disposed on a lower photodiode;
• a first current module in communication with the upper photodiode to measure a first current generated in the upper photodiode in response to light that is incident on the semiconductor structure;
• a second current module in communication with the lower photodiode to measure a second current generated in response to the light that is incident on the semiconductor structure;
• and
• a processor in communication with the first and second current modules to determine the wavelength of the light that is incident on the semiconductor structure in response to the measured first and second currents and a predetermined correspondence between the first and second currents as a function of wavelength.

A device for determining a wavelength of light that is incident on a semiconductor device comprising an upper region of a first conductivity type disposed on a lower region of a second conductivity type opposite the first conductivity type, comprising:

• means for measuring a first current generated in response to light that is absorbed in the upper region;
• means for measuring a second current generated in response to light that is absorbed in the lower region;
• and
• means for determining the wavelength of the light that is incident on the semiconductor device in response to the measured first and second currents and a predetermined correspondence between the first and second currents as a function of wavelength.