High speed detectors having integrated electrical components
View Patent ↗An opto-electronic device configured as a photodetector has a capacitor and/or resistor monolithically formed on a surface of the photodetector. The capacitor capacitively couples the AC ground of the photodetector to the bias terminal of the photodetector. The on chip capacitor design eliminates the inductance of external circuit traces between the power supply and an external capacitor. The resistor forces the AC return current of the photodetector through the AC ground in preference to the typical (DC bias terminal) path. Combinations of capacitors and resistors are particularly effective in reducing crosstalk among adjacent detectors in arrays.
1. An optoelectronic device, comprising:
a semiconductor substrate;
an array of photodetectors formed adjacent the semiconductor substrate each of said photodetectors having an anode and a cathode;
an array of amplifiers, having input terminals and ground terminals, said anodes of said photodetectors coupled to said input terminals; and
one or more monolithic capacitors configured to capacitively couple each of said cathodes of one or more of the photodetectors to one or more of said ground terminals, said capacitors allowing transient voltage applied to said cathode to bypass said photodetector and pass directly to said ground terminal,
wherein a continuous constant bias is applied to said array of photodetectors.
2. The optoelectronic device of claim 1 wherein a plurality of monolithic capacitors couple a plurality of said photodetectors to said one or more bias terminals.
3. The optoelectronic device of claim 1 further comprising one or more bias resistors, wherein said one or more bias resistors couple said one or more photodetectors to said one or more bias terminals.
4. The optoelectronic device of claim 1 wherein a separate monolithic capacitor individually couples each of said one or more photodetectors to said one or more bias terminals.
5. The optoelectronic device of claim 1 further comprising a plurality of monolithic bias resistors, wherein a separate bias resistor is coupled between each of said one or more photodetectors and said one or more bias terminal.
6. The optoelectronic device of claim 1 further comprising a monolithic bias resistor coupled between said one or more photodetectors and a single bias terminal.
7. The optoelectronic device of claim 1 wherein each of said one or more capacitors comprises a dielectric layer formed adjacent to a first electrode and a conductive layer formed adjacent to said dielectric layer and overlapping a portion of said first electrode.