Multicolor photodiode array and method of manufacturing

• US 20060081768A1
• Filed: 09/13/2005
• Published: 04/20/2006
• Est. Priority Date: 09/14/2004
• Status: Active Grant

• Current Assignee: Banpil Photonics, Inc.
• Original Assignee: Banpil Photonics, Inc.
• Inventors: Dutta, Achyut Kumar
• Granted Patent: US 7,535,033 B2
• Time in Patent Office: Days
• US Class Current: 250/214.100
• CPC Class Codes: H01L 2224/4847 the connecting portion on the bonding area of the semiconductor or solid-state body being a wedge bond
• CPC Class Codes: H01L 27/14634 Assemblies, i.e. Hybrid structures
• CPC Class Codes: H01L 27/1464 Back illuminated imager structures
• CPC Class Codes: H01L 27/14645 Colour imagers
• CPC Class Codes: H01L 31/109 the potential barrier being of the PN heterojunction type

Abstract

Novel structures of the photodetector having broad spectral ranges detection capability are provided. The photodetector can offer high quantum efficiency >95% over wide spectral ranges, high frequency response >10 GHz (@3 dB). The photodiode array of N×N elements is also provided. The array can also offer wide spectral detection ranges ultraviolet to 2500 nm with high quantum efficiency >95% and high quantum efficiency of >10 GHz, cross-talk of <1%. In the array, each photodiode can be independently addressable and can be made either as top-illuminated or as bottom illuminated type detector. The photodiode and its array provided in this invention, could be used in multiple purpose applications such as telecommunication, imaging and sensing applications including surveillance, satellite tracking, advanced lidar systems, etc. The advantages of this photodetectors are that they are uncooled and performance will not be degraded under wide range of temperature variation.

Claims

1. A photodiode structure comprising:

an n-type ohmic contact layer;

an n-type InP (or GaAs) substrate etched out from backside and connected to part of the n-type contact layer;

a single or plurality of n-type buffer layer(s) attached to the n-type substrate;

an InGaAs absorption layer attached to the buffer layer;

a spacer layer attached to the absorption layer;

a highly doped p-type Indium (In)-based ohmic contact layer attached to the spacer layer, and;

an p-type ohmic contact on the surface of the p-type contact layer.

2. The photodiode of claim 1 where all n-type materials are replaced with p-type materials and all p-type materials are replaced with n-type materials.

3. The photodiode of claim 1 where the n-type ohmic contact layer is removed and replaced with a volume of n-type ohmic material that makes contact with the n-type InP substrate on the side connected to the n-type contact layer, continues through all the other layers, terminates on the open side of the p-type InGaAs ohmic contact layer, and is insulated from all layers but the n-type InP substrate by a non conductive material to allow access from the top of the device.

4. The photodiode of claim 1 where etched out back-side of the substrate is circular, rectangular, square, or elliptical in shape.

5. The photodiode of claim 1 where doped p-type Indium (in)-based ohmic contact layer is a single InGaAs or a combination of InGaAs and InP.

6. The photodiode of claim 1 where antireflection (AR) coating is used on back side of the etched substrate.

7. The photodiode of claim 1 wherein thickness of the n-type contact layer is 5 to 200 nm, designed to have the field distribution enough avoiding the diffusion related current.

8. A photodiode structure comprising:

an n-type InP substrate etched out from backside;

a single or plurality of n-type buffer layer(s) attached to the n-type substrate;

an InGaAs absorption layer connected to the buffer layer; and

a single or plurality of doped p-type In-based ohmic contact layer(s) connected to the absorption layer, and;

an p-type ohmic contact on the surface of the p-type contact layer.

9. The photodiode of claim 8 where the buffer layer is composed of a thin layer of InP and a layer of low doped InAsP.

10. The photodiode of claim 8 where the p-type In-based ohmic contact layer(s) are composed of InAs_0.6P_0.4 layer and highly doped InP.

11. The photodiode of claim 8 where the p-type InAs_0.6P_0.4 layer is single layer or the the combination of InAs_0.6P_0.4 and InAs_yP_1-y and/or their graded composition layers.

12. The photodiode of claim 8 where the p-type InAs_0.6P_0.4 layer is single layer or the combination of highly doped InAs_0.6P_0.4 and InP.

13. The photodiode of claim 8 where all n-type materials are replaced with p-type materials and all p-type materials are replaced with n-type materials.

14. The photodiode of claim 8 where the n-type ohmic contact layer is removed and replaced with a volume of n-type ohmic material that makes contact with the n-type InP substrate on the side connected to the n-type contact layer, continues through all the other layers, terminates on the open side of the p-type InGaAs ohmic contact layer, and is insulated from all layers but the n-type InP substrate by a non conductive material to allow access from the top of the device.

15. The photodiode of claim 8 where antireflection (AR) coating is used on back side of the etched substrate.

16. An array device comprising:

an n-type substrate etched out from backside and connected to part of the n-type contact layer;

a single or plurality of n-type buffer layer(s) attached to the n-type substrate;

a single or plurality of InGaAs absorption layer(s) connected to the buffer layer(s) with an array of sections etched into the absorption layer to electrically isolate each section;

a group of doped p-type In-based ohmic contact layer(s) on each isolated section of the absorption layer, and;

a group of highly doped p-type ohmic contacts with separate contacts for each isolated section of the absorption layer.

17. The array device of claim 16 where substrate can be InP, GaAs, or GaN.

18. The array device of claim 16 where the buffer layer is composed of a thin layer of InP and a layer of low doped InAsP.

19. The array device of claim 16 where the p-type In-based ohmic contact layer(s) are composed of InAs_0.6P_0.4 layer and highly doped InP.

20. The array device of claim 16 where all n-type materials are replaced with p-type materials and all p-type materials are replaced with n-type materials.