Photodetector Array Resistive Pixel Protection
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Solution Overview
Problem
Thin film photodetector arrays are vulnerable to abrupt failures due to defects, leading to electrical shorts and reduced sensitivity, as the thin active layer between electrodes can cause heat generation and damage to surrounding pixels.
Innovation Solution
Incorporating a resistive element in series with each pixel's photon radiation sensitive element, with a resistive value between 0.05 to 0.2 times that of the switching element, to limit current and mitigate damage from defects, and using thin film resistors or modified semiconductor regions to achieve this.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a thin film photodetector array uses a very thin active layer (less than 500 nm) between electrodes to reduce device thickness and simplify manufacturing, then device thinness and manufacturing simplicity are improved, but vulnerability to defects and electrical shorts increases
Solution Approach 1:
The patent introduces a protective layer between the photodetector array and readout electronics that acts as a buffer against defect propagation. This layer includes a first insulating layer and a second insulating layer with through-openings, creating physical separation and protection before defects can cause catastrophic failure of the entire system.
Solution Approach 2:
The patent introduces intermediate insulating layers and protective structures between the thin photodetector active layer and the readout electronics. These intermediary layers serve as mediators that prevent direct electrical shorts while allowing the thin active layer to maintain its sensing function, thus protecting the system without compromising the thinness advantage.
2Reliability
If defect-free manufacturing is pursued to eliminate electrical shorts and heat generation, then reliability is improved, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent converts the harmful effect of defects by introducing protective insulating layers that contain and isolate defects when they occur. Rather than attempting to eliminate all defects through complex manufacturing, the design accepts that defects may occur but prevents them from propagating, thus converting the potential harm into a manageable condition that doesn't compromise overall system reliability.
Solution Approach 2:
The protective insulating layer structure is built in advance during manufacturing, creating a cushion of protection before defects can cause damage. This approach allows standard manufacturing processes to be used without requiring defect-free production, as the protective structure is already in place to handle any defects that may arise during operation.
3Measurement precision
If a large photodiode area is used to improve light sensitivity, then detection sensitivity is improved, but the impact of defects on overall performance increases
Solution Approach 1:
The patent segments the photodetector array into individual pixel units with isolated readout circuits. Each pixel's readout circuit is separated by insulating layers, so that a defect in one pixel cannot affect neighboring pixels. This segmentation allows each photodiode to be large for sensitivity while preventing defect propagation across the entire array.
Solution Approach 2:
The insulating layers act as intermediaries that separate individual photodetector pixels and their readout circuits. This intermediary structure allows each pixel to operate independently with large photodiode area for sensitivity, while preventing defects in one pixel from affecting other pixels through electrical shorts or heat generation.
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 solution reduces the risk of damage to surrounding pixels and allows for minor performance changes to be compensated through image processing, maintaining the photodetector array's functionality even with defective pixels.
Implementation Method 1
Respective pixels comprise a photon radiation sensitive element arranged in a series connection with a switching element
Implementation Method 2
The series connection further includes a resistive element. In the inadvertent case that a photodiode in the photodetector array contains a defect and this happens to cause an electrical short of the photodiode, the current of the pixel containing this photodiode is limited to the level designed by the thin-film resistor
Data Source
AI summary
A photodetector array (1) is provided comprising a plurality of pixels (10ij) between a supply line (4j) and a common electrode (2). Respective pixels (10ij) comprise a photon radiation sensitive element (11ij) arranged in a series connection with a switching element (20ij) characterized in that the series connection further includes a resistive element (30ij).