AlGaN UV Sensor with Integrated ROIC for Accurate Indexing
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Solution Overview
Problem
Current UV index measurement devices using silicon-based sensors are inaccurate due to their inability to directly detect UVB light, relying on visible light and UVA intensity, leading to errors and requiring expensive filters, while also being inconvenient for users who need to manually operate applications to calculate UV exposure metrics.
Innovation Solution
A UV measuring device employing an AlxGa(1−x)N-based UV sensor, integrated with a read-out integrated circuit (ROIC) on a sapphire substrate, which directly detects UV light across various bands without filters, providing accurate digital output and improved resistance to electrostatic discharge, and is integrated into a portable digital assistant for automatic UV index calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If silicon-based sensors are used for UV index measurement, then the device can detect visible light and UVA intensity, but the measurement accuracy deteriorates because the sensor cannot directly detect UVB light
Solution Approach 1:
The patent segments the UV detection function by using multiple photodetector elements with different spectral response characteristics. Specifically, it employs a first photodetector element for UVA detection and a second photodetector element for UVB detection, allowing each element to specialize in a specific wavelength band. This segmentation enables accurate UV index measurement by directly detecting both UVA and UVB components separately, resolving the contradiction between measurement accuracy and wavelength detection capability.
Solution Approach 2:
The patent uses composite material structures for the photodetector elements, including semiconductor layers with specific bandgap energies tailored for different UV wavelength ranges. The first photodetector element uses materials optimized for UVA detection while the second uses materials with appropriate bandgaps for UVB detection. This composite approach enables simultaneous detection of multiple UV bands with high accuracy, addressing both the measurement precision and wavelength versatility requirements.
2Measurement precision
If filters are added to silicon-based UV sensors to improve measurement accuracy, then the measurement precision improves, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts the wavelength-selective function from external optical filters and integrates it directly into the photodetector elements themselves. By designing photodetector elements with specific semiconductor materials and bandgap energies, the wavelength selection is built into the detection mechanism rather than requiring separate filter components. This eliminates the need for complex filter structures while maintaining high measurement precision for both UVA and UVB detection.
Solution Approach 2:
The patent replaces the mechanical/optical filter system with an electronic/semiconductor-based wavelength selection mechanism. Instead of using physical filters to separate wavelengths, the system uses photodetector elements with different semiconductor bandgaps that inherently respond to different UV wavelength ranges. This substitution simplifies the device structure by eliminating mechanical filter components while achieving the same wavelength discrimination function through material properties.
3Ease of manufacture
If Schottky junction type UV detection elements are used, then the manufacturing process is simplified, but the resistance to electrostatic discharge deteriorates
Solution Approach 1:
The patent merges the advantages of both Schottky junction and PIN structure by integrating photodetector elements with improved electrostatic discharge protection into a unified detector array. The system combines the manufacturing simplicity of Schottky junctions with additional protective structures and circuitry that enhance ESD resistance. By merging these functional elements into a single integrated UV detector system, the patent maintains ease of manufacture while improving reliability against electrostatic discharge.
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 solution significantly enhances UV light measurement accuracy across broad wavelength bands, simplifies manufacturing, eliminates the need for filters, and provides automatic UV index calculation, enhancing user convenience by integrating the UV sensor with a portable digital assistant.
Implementation Method 1
A semiconductor photodetector is a semiconductor device configured to operate using a principle that electric current flows in response to application of light
Implementation Method 2
a depletion region is generated by separation of holes and electrons in the semiconductor upon irradiation with light such that electric current flows therein due to the flow of electrons
Data Source
AI summary
Disclosed are an ultraviolet measuring device, a photodetector, an ultraviolet detector, an ultraviolet index calculation device, and an electronic device or portable terminal including the same. In one aspect, an ultraviolet measuring is provided to comprise: a substrate on which an electrode is formed; a readout integrated circuit (ROTC) unit electrically connected with the electrode; and an aluminum gallium nitride (AlGaN) based UVB sensor electrically connected with the readout integrated circuit unit and formed on an insulating substrate, wherein the read-out integrated circuit converts a photocurrent input from the UV sensor into a digital signal including UV data.