Semiconductor Photon Detector with Rear Bias Layer
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Solution Overview
Problem
Current semiconductor structures for photon detection face challenges in cost-effective production and efficient photon detection, particularly due to high costs associated with contacting the bias layer and limited depletion zone extent, leading to recombination of charge carriers and reduced detection efficiency.
Innovation Solution
A semiconductor structure with a substrate, contact region, bias layer, and guard ring, where the guard ring surrounds the contact area and applies a blocking voltage, allowing for a larger overlap area that influences the potential of the bias layer, reducing the need for rear-side contacting and enabling a more extensive depletion zone for efficient photon detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the bias layer is contacted through the substrate using wire bonding or TSV, then the electrical connection is established, but the production cost increases significantly
Solution Approach 1:
The patent extracts the bias layer from the substrate and places it on the rear side, allowing it to be influenced by the contact area's potential without requiring direct contacting. This separation eliminates the need for complex wire bonding or TSV structures while maintaining electrical functionality through the overlapping area configuration.
Solution Approach 2:
The overlapping area between the contact area and bias layer acts as an intermediary region. The potential from the contact area is transmitted through this overlap region to influence the bias layer, serving as a mediator that eliminates the need for direct electrical contact while maintaining the necessary electrical influence.
2Area of stationary object
If the contact area is small, then the device size is reduced, but the depletion zone extent is limited causing charge carrier recombination
Solution Approach 1:
The patent extends the depletion zone formation into the lateral dimension through the overlapping area configuration. By creating an overlap region between the contact area and bias layer, the depletion zone extends laterally beyond the contact area boundaries, increasing the effective detection volume without increasing the contact area footprint.
Solution Approach 2:
The patent segments the functional regions into distinct contact area and bias layer regions on opposite sides of the substrate. This segmentation allows each region to be optimized independently - the contact area for electrical connection and the bias layer for depletion zone formation - while their overlapping projection creates an extended effective area for charge carrier collection.
3Reliability
If the blocking voltage is applied between contact area and guard ring, then charge carrier separation is improved, but the voltage requirements increase
Solution Approach 1:
The patent applies different doping levels to different regions - the substrate has a first doping type while the bias layer has a second doping type. This local quality differentiation creates favorable conditions for depletion zone formation and charge carrier separation, enabling effective separation at lower voltage requirements compared to uniformly doped structures.
Solution Approach 2:
The guard ring is configured to create equipotential regions that facilitate charge carrier separation. By maintaining appropriate potential distribution through the guard ring structure, the patent achieves effective charge carrier separation while optimizing the voltage requirements through controlled potential equipotential zones.
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 configuration reduces production costs, enhances photon detection efficiency by minimizing recombination, and allows for effective charge carrier separation and detection, particularly in the infrared range, with reduced voltage requirements and improved light penetration.
Implementation Method 1
If an electron-hole pair is generated by the absorption of a photon in this depletion zone, they are separated due to the electric field in the depletion zone.
Implementation Method 2
The bias layer on the back can be used to produce a depletion zone between areas on the front with a doping of the first type (substrate contact) and the bias layer.
Data Source
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AI summary
The structure i.e. photodetector (1), has a bias-layer (4) made of a semiconductor material and arranged on a rear side of a substrate (2) spaced from a contact area (3) i.e. tub. The contact area is partially laid opposite to the bias-layer. A protective structured guard ring (5) is arranged on a front side of the substrate, and surrounds the contact area. Reverse voltage is applied between the contact area and the ring. An overlap region exhibits lateral dimension, which is quarter of distance between the contact area and the bias-layer. The substrate is made of floating zone silicone.