Dual Gate Oxide Semiconductor Optical Sensor Element
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Solution Overview
Problem
Existing photoelectric conversion devices face challenges such as high cost, decreased yield ratio, and temperature-dependent performance due to the use of separate processes for oxide semiconductor TFTs and amorphous silicon PIN diodes, as well as limited light sensitivity across the visible spectrum, particularly with red light, in oxide semiconductor-based optical sensors.
Innovation Solution
The development of an optical sensor element using a dual gate type oxide semiconductor thin film with gate electrodes on both sides and a voltage application unit that applies different voltages to each gate electrode, enhancing light sensitivity across the visible spectrum by generating photocarriers even with light having energy less than the band-gap energy through a potential gradient.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate processes are used for oxide semiconductor TFTs and amorphous silicon PIN diodes, then photoelectric conversion performance is improved, but manufacturing cost increases and yield ratio decreases
Solution Approach 1:
The patent combines the oxide semiconductor TFT and amorphous silicon PIN diode into a single integrated optical sensor element structure. The oxide semiconductor layer serves as the active layer for the TFT while the amorphous silicon layer forms the PIN diode, allowing both components to share common electrodes and insulating films. This integration eliminates separate manufacturing processes, reduces production complexity, and lowers manufacturing costs while maintaining the photoelectric conversion performance of both materials.
2Reliability
If separate processes are used for oxide semiconductor TFTs and amorphous silicon PIN diodes, then photoelectric conversion performance is improved, but yield ratio decreases
Solution Approach 1:
The integrated structure allows both the oxide semiconductor TFT and amorphous silicon PIN diode to be manufactured in a single fabrication process sequence. Common layers such as the first insulating film, second insulating film, and electrode structures serve dual purposes for both components. This unified manufacturing approach reduces process variations and defects, thereby improving the yield ratio while maintaining the high photoelectric conversion performance required for optical sensing applications.
3Ease of manufacture
If oxide semiconductor is used in optical sensor, then manufacturing cost is reduced, but light sensitivity across visible spectrum is limited
Solution Approach 1:
The patent employs a composite material structure where the oxide semiconductor layer (e.g., In-Ga-Zn-O) is combined with the amorphous silicon layer. The oxide semiconductor provides cost-effective manufacturing and good electrical characteristics, while the amorphous silicon layer enhances light sensitivity across the visible spectrum through its appropriate bandgap energy. This composite structure allows the optical sensor to benefit from both materials' advantages, achieving full visible spectrum sensitivity while maintaining manufacturing cost benefits.
4Ease of manufacture
If oxide semiconductor is used in optical sensor, then manufacturing cost is reduced, but temperature-dependent performance issues occur
Solution Approach 1:
The integrated composite structure combines oxide semiconductor and amorphous silicon materials that complement each other's temperature characteristics. The amorphous silicon PIN diode portion provides stable photoelectric conversion characteristics over a wide temperature range, compensating for the oxide semiconductor's temperature sensitivity. This material combination allows the optical sensor to maintain reliable performance across varying temperatures while preserving the manufacturing cost advantages of using oxide semiconductor technology.
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 improves light sensitivity across the visible spectrum, reduces manufacturing costs, and minimizes temperature-dependent performance issues, enabling stable and efficient photoelectric conversion.
Implementation Method 1
the optical sensor that uses the PIN diode absorbs almost all of light beams with wavelengths in the visible light region, and generates a carrier
Implementation Method 2
generating photocarriers even with light having energy less than the band-gap energy through a potential gradient
Data Source
AI summary
Two gate electrodes are provided on upper and lower sides of an oxide semiconductor active layer through respective insulating films. In addition, a first read-out electrode and a second read-out electrode are provided on right and left sides of the oxide semiconductor active layer. In the optical sensor element, in a case where a voltage is applied to each gate electrode, a potential difference occurs between the first read-out electrode and the second read-out electrode, and intensity of irradiation light is detected based on a current that flows between the read-out electrodes.