Barrier Photodetector Pixel Isolation via Ion Damage
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Solution Overview
Problem
Existing barrier-type photo-detectors face challenges in manufacturability, reliability, and production yield due to the need for material removal to isolate pixels, which can introduce defects and increase dark current.
Innovation Solution
The solution involves non-etched or partially etched contact layers with delineated pixel regions and a Barrier interface grading that allows minority carrier flow while blocking majority carriers, using ion-damaged or doped regions to impede lateral carrier flow and reduce dark current, enabling two-color operation through bias voltage reversal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If material removal is used to isolate pixels in barrier-type photo-detectors, then pixel delineation is achieved, but manufacturing complexity and defect introduction increase
Solution Approach 1:
The patent extracts the pixel isolation function from the contact layer by using the barrier layer as the primary isolation structure. The barrier layer extends beyond the pixel regions to provide electrical isolation, eliminating the need to etch or remove contact layer material for pixel delineation. This maintains manufacturing simplicity while achieving effective pixel isolation.
Solution Approach 2:
The patent shifts the isolation function from the lateral dimension (contact layer etching) to the vertical dimension (barrier layer extension). By having the barrier layer extend laterally beyond the pixel regions and maintain its blocking function, the patent achieves pixel isolation through vertical structure design rather than lateral material removal.
2Manufacturing precision
If material removal is used to isolate pixels, then pixel separation is achieved, but reliability decreases due to introduced defects
Solution Approach 1:
The patent removes the need for contact layer etching by extracting the isolation function to the barrier layer. Since no material removal is performed on the contact layer, defects such as etch damage, surface states, and structural weaknesses are eliminated, maintaining layer integrity and device reliability.
Solution Approach 2:
The barrier layer is designed to extend beyond the pixel regions beforehand to provide a cushioning isolation effect. This pre-designed barrier extension prevents the need for subsequent material removal operations that would introduce defects, thereby protecting the contact layer from damage.
3Manufacturing precision
If complete etching is used to isolate pixels, then pixel isolation is achieved, but production yield decreases
Solution Approach 1:
The patent extracts the isolation function from the contact layer etching process and assigns it to the barrier layer structure. This eliminates the need for complete contact layer etching, reducing process complexity and increasing production yield while maintaining effective pixel isolation.
Solution Approach 2:
Instead of requiring complete contact layer etching, the patent uses partial barrier layer extension beyond the pixel regions to achieve sufficient isolation. This partial action approach reduces manufacturing steps and increases yield while maintaining the necessary pixel separation function.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves reliability, radiation hardness, and production yields by eliminating material removal steps, reducing surface states, and enhancing two-color operation without increasing noise or defects, while maintaining effective carrier blocking and minority carrier transport.
Implementation Method 1
the effective conduction and valance band alignments for the two layers and Barrier are arranged so as to allow photo-generated minority carrier flow but filter or block majority carrier flow
Implementation Method 2
the Barrier conduction and valance band edges are aligned with respect to the first and second layer energy bands so as to allow minority carrier current flow while blocking majority carrier current flow between the first and second layers
Implementation Method 3
In some embodiments, the non-pixel regions are ion-damaged regions. In such embodiments, the ion damage prevents carrier transport through the non-pixel regions.
Implementation Method 4
the non-pixel regions are doped regions of a first doping type and the pixel regions are doped regions of a second doping type
Implementation Method 5
Barrier interface grading for dark current reduction
Implementation Method 6
at least one of the semiconductor layers is used for photo-absorption
Implementation Method 7
photo-generated minority carrier flow
Data Source
AI summary
A barrier-type photo-detector is provided with a Barrier between first and second layers. One of the layers is delineated into pixels without fully removing the non-pixel portions of the delineated layer. Delineation may be accomplished through material modification techniques such as ion damage, selective doping, ion induced disordering or layer material growth. Some variations may employ partial material removal techniques.