Backside configured surface plasmonic structure for infrared photodetector and imaging focal plane array enhancement
The invention relates to quantum dot and photodetector technology, and more particularly, to quantum dot infrared photodetectors (QDIPs) and focal plane array. The invention further relates to devices and methods for the enhancement of the photocurrent of quantum dot infrared photodetectors in focal plane arrays.
1. A method of producing a focal plane array comprising,
a) formation of a two dimensional hole array plasmonic structure upon a QDIP structure using photolithography, followed by deposition of metal to form a mesa,
b) patterning of said mesa using photolithography, followed by wet etch stopping at the bottom contact layer of said QDIP structure,
c) formation of ohmic contacts,
d) deposition of a passivation layer,
e) opening of a connection to the ohmic contact through passivation layer,
f) patterning and deposition of an indium bump, and
g) hybridization of said indium bumps to a read out integration circuit.
2. The method of claim 1 , wherein said metal deposited to form a mesa comprises gold.
3. The method of claim 1 , wherein said mesa is between 75 and 30 nm.
4. The method of claim 1 , wherein said mesa is circular.
5. The method of claim 1 , wherein step c) comprises:
i) masking said QDIP structure; and
ii) patterning said ohmic contacts using photolithography, followed by deposition of metal and lift off of said to finish the ohmic contacts.
6. The method of claim 5 , wherein said method further comprises rapid thermal annealing.
7. The method of claim 5 , wherein said metal comprises Ni/Ge/Au/Ni/Au.
8. The method of claim 7 , wherein said metal thicknesses comprise Ni(50 Å)/Ge(170 Å)/Au(330 Å)/Ni(150 Å)/Au(3000 Å).
9. The method of claim 1 , wherein step d) further comprises deposit low stress Si 3 N 4 .
10. The method of claim 1 , wherein step e) comprises opening to the ohmic contact metal using an inductively coupled plasma reactive ion etch system.
11. The method of claim 1 , wherein step f) comprises deposition of Cr/In and lift-off.
12. The method of claim 11 , wherein said deposition further comprises deposition of 150 Å Cr and 5 μm In.