COMPOUND SEMICONDUCTOR LIGHT-RECEIVING ELEMENT ARRAY

• US 20120286328A1
• Filed: 01/11/2011
• Published: 11/15/2012
• Est. Priority Date: 01/25/2010
• Status: Active Grant

• Current Assignee: Irspec Corporation
• Original Assignee: Irspec Corporation
• Inventors: Ogura, Mutsuo, Nishida, Katsuhiko
• Granted Patent: US 8,610,170 B2
• Time in Patent Office: Days
• US Class Current: 257/188
• CPC Class Codes: H01L 27/14649 Infrared imagers
• CPC Class Codes: H01L 27/14694 The active layers comprising only AIIIBV compounds, e.g. GaAs, InP
• CPC Class Codes: H01L 31/1035 the devices comprising active layers formed only by AIIIBV compounds

Abstract

An array structure solves issues that exist in conventional compound semiconductor photodiode arrays, such as large cross talk, large surface leaks, large stray capacitance, narrow detection wavelength bands, and bad manufacturing yield, simultaneously. A photodiode array has, laminated upon a semiconductor substrate, a buffer layer (8) with a broad forbidden band width, an I-type (low concentration photosensitive layer (2) with a narrow forbidden band width, and an n-type semiconductor window layer (3) with a broad forbidden band width, wherein photodiode elements are electrically separated from adjacent elements, by doping the periphery of the p-type impurity, and the detection wavelength band is expanded, by making the n-type window layer (3) on the photosensitive layer (2) a thinner layer with crystal growth.

Claims

1. A compound semiconductor-based photo-detector array comprising:

a barrier layer comprising a wider energy bandgap compound semiconductor;

a photo-sensitive layer comprising a narrower energy bandgap formed on the said barrier layer;

a window layer of a first conductivity type comprising a wider energy bandgap formed on said photo-sensitive layer;

wherein boundaries of the photo-sensitive layer and window layer of each of elements are at least doped with a second conductivity type impurity to isolate the adjacent elements.

2. A compound semiconductor-based photo-detector array according to claim 1, wherein the boundary of the photo-sensitive layer and window layer is isolated with a mesa structure;

and surfaces of the mesa structure at mesa-side walls and bottom part thereof are doped with the second conductivity type impurity.

3. A compound semiconductor-based photo-detector array according to claim 1, wherein in case a band offset of conduction and valence band at a bonding surface between said window layer and said photo-sensitive layer are defined as Δ

Ec₂₃ and Δ

Ev₂₃, respectively, Δ

Ec₂₃ is smaller than Δ

Ev₂₃ when said window layer is P-type, while Δ

Ec₂₃ is larger than Δ

Ev₂₃ when said window layer is N-type.

4. A compound semiconductor-based photo-detector array according to claim 1, wherein N and P type electrodes are formed at opposite sides of a substrate and an incident light is projected from a substrate side.

5. A compound semiconductor-based photo-detector array according to claim 1, wherein single element or column of the arrays of the elements are electrically isolated from others with grooves which are formed in doped regions with the second conductivity type.

6. A compound semiconductor-based photo-detector array according to claim 1, wherein a photo-sensitive region is formed on a strain relaxation layer in which a lattice constant is different from a substrate.