ROIC Electrode Grid for CQD Photodetector Pixel Delineation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Colloidal quantum dot (CQD) film photodetectors face challenges in proper pixel definition and electrical conduction when integrated with readout integrated circuits (ROICs), particularly due to the lack of internal structures to channel current to each pixel, leading to difficulties in detecting electromagnetic radiation effectively.
Innovation Solution
A monolithic integration approach is employed, where an electrode grid is added to the ROIC prior to the deposition of the photodetector film, providing electrical contact and pixel delineation without the need for etching or post-deposition processing, using conductive materials like gold, copper, or indium tin oxide, ensuring proper voltage biasing and direct pixel definition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a colloidal quantum dot film is deposited directly onto a readout integrated circuit without additional electrode structures, then the device complexity is reduced, but proper pixel definition and electrical conduction cannot be achieved
Solution Approach 1:
The electrode grid is formed on the ROIC substrate before depositing the colloidal quantum dot film. This preliminary action ensures that the electrode structures are in place to provide proper pixel definition and electrical conduction pathways before the photosensitive material is applied, eliminating the need for post-deposition etching or processing
Solution Approach 2:
The electrode grid is segmented into multiple discrete electrodes corresponding to individual pixels, with each electrode providing independent electrical contact to its associated pixel region. This segmentation enables proper pixel definition by creating distinct electrical zones that prevent cross-talk between adjacent pixels while maintaining simple fabrication
2Manufacturing precision
If traditional hybridization methods with separate ROIC and photodetector arrays are used, then proper pixel definition can be achieved, but the manufacturing process becomes more complex and requires additional processing steps
Solution Approach 1:
The invention merges the ROIC substrate and photodetector array fabrication into a single integrated process. The electrode grid is formed on the ROIC, followed by direct deposition of the colloidal quantum dot film to create the photodetector array, eliminating the need for separate fabrication and hybridization steps required by traditional methods
Solution Approach 2:
The electrode grid structure is preliminarily formed on the ROIC before photodetector film deposition, providing built-in pixel definition that eliminates the need for subsequent etching or post-deposition processing steps required in traditional hybridization approaches
3Device complexity
If no adjacent electrodes are provided for pixel delineation, then the device structure remains simple, but cross-talk between adjacent pixels increases and detection precision deteriorates
Solution Approach 1:
The electrode grid divides the photodetector film into distinct pixel regions, with each electrode serving as a boundary that electrically isolates adjacent pixels. This segmentation prevents carrier diffusion and signal cross-talk between pixels while maintaining a relatively simple overall device structure
Solution Approach 2:
Adjacent electrodes are strategically positioned at pixel boundaries to provide localized electrical isolation where it is most needed. The electrodes create regions of different electrical potential that confine charge carriers to their respective pixel regions, improving detection precision without requiring complex global restructuring
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 method allows for efficient electrical signal flow between sensing electronics and the CQD film, enabling effective detection of photons and reducing cross-talk, thereby improving imaging performance without additional processing steps.
Implementation Method 1
Certain materials, material systems, material composites and material structures known collectively as photosensors or photodetectors are capable of producing a detectable change in electrical signal(s), such as a current or changing conductance, when light or waves of electromagnetic radiation are intercepted by the photodetector
Implementation Method 2
These quantum dots possess quantized allowable energies for electron states within each dot. Due to each dot's restricted physical size, these energy states may not represent those present in the same materials in bulk form due to quantum confinement. When a photon is intercepted by such a dot, it may be absorbed and excite an electron into another allowable quantum state within the dot
Implementation Method 3
This excited electron may then move from its origination dot to any other dot in the film even if classically forbidden via quantum mechanical tunneling, with a very strong preference for those in immediate physical proximity
Data Source
AI summary
A photodetector device is provided that includes a ROIC having a top surface with a plurality of electrically conductive first electrodes within a pattern of surface areas on the top surface each surface area having a border, and an electrically conductive electrode grid having a portion on the border of each of the surface areas; and a photodetector film overlying the surface area. The electrode grid can be configured to surround each surface area to define the borders of the surface areas as pixels. The photodetector film can be a colloidal quantum dot film. The ROIC has circuit elements signal-connected to the plurality of first electrodes. Methods for forming the photodetector device include photolithography and deposition methods.