Nanoscale Light Spot Position Detection Using 3D Pillar Array Photo Detectors
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Solution Overview
Problem
Current light spot position detectors using 2D thin film photo sensitive devices face limitations in resolution due to electron diffusion and noise, which cannot be effectively improved beyond micrometer scale without increasing manufacturing complexity and vulnerability to noise.
Innovation Solution
The development of a 3D pillar array photo detector using vertically aligned nanorods, such as zinc oxide (ZnO), which confines light-excited electrons within nanoscale volumes, overcoming electron dispersion and achieving nanoscale resolution by adjusting the height and diameter of the nanorods to enhance photoelectric detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If 2D thin film photo sensitive devices are used, then manufacturing is simpler, but resolution is limited to micrometer scale due to electron diffusion
Solution Approach 1:
The patent transitions from 2D thin film photo detectors to 3D pillar array structures with vertically aligned nanorods. This dimensional change confines photo-generated carriers within individual nanorod columns, preventing lateral electron diffusion that limits 2D devices. The 3D structure enables nanoscale resolution (200 nm demonstrated, potentially down to 10 nm) while maintaining manufacturing feasibility through vertical growth processes.
2Measurement precision
If pixel size is reduced to improve resolution, then measurement precision increases, but noise vulnerability increases
Solution Approach 1:
The patent divides the photo sensitive material into discrete, isolated nanorod pillars arranged in arrays. Each nanorod acts as an independent detection element with confined charge carriers, eliminating cross-talk and noise from adjacent regions. This segmentation approach enables small effective pixel sizes with inherent noise isolation, achieving high resolution without proportionally increasing noise vulnerability.
3Measurement precision
If detection volume is increased to improve signal, then photo detection performance improves, but device area increases
Solution Approach 1:
The patent employs a hierarchical nested structure where high-aspect-ratio nanorods (large vertical detection volume) are densely packed within a compact planar footprint. The vertical dimension provides extensive light absorption volume for strong signals, while the horizontal arrangement of nanorod arrays maintains a small overall device area. This nested configuration decouples detection volume from device footprint.
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
The 3D pillar array photo detector achieves ultra-high nanoscale resolution and improved photo detection performance, with measured resolutions of 200 nm and potentially down to 10 nm, while reducing pixel size and increasing detection volume, enabling precise light spot position detection with low noise and cost-effective mass production.
Implementation Method 1
confines light-excited electrons within nanoscale volumes
Data Source
AI summary
Various examples are provided for pillar array photo detectors. In one example, among others, a photo detection system includes an array of substantially aligned photo sensitive nanorods extending between first and second electrodes, and a plurality of resistance monitoring circuits coupled at different positions about the circumference of the electrodes. In another example, a photo detector includes first and second electrodes, and an array of substantially aligned photo sensitive nanorods extending between the substantially parallel electrodes. Light passing through an electrode excites electrons in the photo sensitive nanorods that are illuminated by the light. In another example, a method includes illuminating a portion of a photo detector including an array of substantially aligned photo sensitive nanorods with a light spot, obtaining resistance measurements at a plurality of locations around the array, and determining a position of the light spot on the photo detector based upon the resistance measurements.