Oxide Semiconductor Transistors for Photosensor Off-State Current Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor devices with photosensors face high power consumption due to off-state current in transistors using amorphous or polycrystalline silicon, which increases when not in use during read operations.
Innovation Solution
The use of oxide semiconductor layers for transistors in photosensors, including a photodiode, first, second, and read control transistors, to minimize off-state current and reduce power consumption by varying resistance based on incident light, allowing for low power operation during non-read periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transistors using amorphous silicon or polycrystalline silicon are used in photosensor, then the photosensor can convert output signal into voltage signal, but off-state current passes through the transistor causing power consumption to increase with time
Solution Approach 1:
The patent changes the material parameter of the transistor from amorphous/polycrystalline silicon to oxide semiconductor, which fundamentally alters the electrical characteristics to achieve ultra-low off-state current while maintaining signal conversion capability
Solution Approach 2:
The patent employs oxide semiconductor material as a composite solution that combines the beneficial properties of low off-state current with adequate charge storage capability, resolving the contradiction between signal conversion and power consumption
2Use of energy by moving object
If oxide semiconductor transistors are used to reduce off-state current, then power consumption decreases, but the ability to store charge and convert signal may be affected
Solution Approach 1:
The patent applies local quality by using oxide semiconductor specifically in the transistor channel region where low off-state current is critical, while maintaining other functional regions with properties optimized for charge storage and signal conversion
Solution Approach 2:
The patent utilizes the dynamic characteristics of oxide semiconductor transistors that can be switched between different resistance states, enabling both charge storage during the accumulation phase and signal conversion during the readout phase
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 significantly reduces power consumption by minimizing off-state current and enabling efficient operation across a wide range of light intensities, achieving low power consumption and high-resolution image capture.
Implementation Method 1
The photodiode has a function of supplying charge based on incident light to a gate of the first transistor
Data Source
AI summary
An object is to achieve low-power consumption by reducing the off-state current of a transistor in a photosensor. A semiconductor device including a photosensor having a photodiode, a first transistor, and a second transistor; and a read control circuit including a read control transistor, in which the photodiode has a function of supplying charge based on incident light to a gate of the first transistor; the first transistor has a function of storing charge supplied to its gate and converting the charge stored into an output signal; the second transistor has a function of controlling reading of the output signal; the read control transistor functions as a resistor converting the output signal into a voltage signal; and semiconductor layers of the first transistor, the second transistor, and the read control transistor are formed using an oxide semiconductor.