Double-Gate Thin Film Transistor Light Shielding
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Solution Overview
Problem
Existing thin film transistors face issues with light-induced deterioration of electrical characteristics, leading to increased OFF current and shifted ON voltage, which affects the performance of active matrix liquid crystal and organic electroluminescence displays, and current solutions require additional production steps for light-shielding layers.
Innovation Solution
A double-gate thin film transistor design with a first gate electrode and second gate electrode electrically connected through gate insulating layers to provide comprehensive light-shielding without increasing production steps, using an amorphous oxide semiconductor with Zn, Ga, and Sn, where the first gate electrode shields from below, the second gate electrode shields from above, and both act as side-wall light-shielding layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If separate light-shielding layers are formed above, below, and on side walls of the semiconductor layer, then light-shielding ability is improved, but the number of production steps increases
Solution Approach 1:
The patent merges the light-shielding function with the gate electrode structure by forming the gate electrode to extend along side walls of the semiconductor layer. This integration eliminates the need for separate side-wall light-shielding layers, reducing production steps while maintaining comprehensive light-shielding ability from above, below, and sides.
Solution Approach 2:
The gate electrode is designed to serve multiple functions simultaneously: it provides electrical gating control and acts as a light-shielding layer. By making the gate electrode extend along the side walls, it universally shields light from all directions (above, below, and sides) without requiring additional dedicated light-shielding components.
2Adaptability or versatility
If transparent amorphous oxide semiconductor is used as semiconductor layer, then flexibility and transparency are improved, but light-induced deterioration of electrical characteristics occurs
Solution Approach 1:
The patent applies preliminary anti-action by forming gate electrodes that extend along the side walls of the semiconductor layer before light exposure occurs. This pre-configured light-shielding structure prevents light from reaching the semiconductor layer from all directions, counteracting the light-induced deterioration of electrical characteristics while maintaining the benefits of using transparent amorphous oxide semiconductor.
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 design achieves high light-shielding ability and improved drive performance by spatially close light-shielding layers, reducing the impact of light on the semiconductor layer and maintaining the desired threshold voltage, thus enhancing the stability and efficiency of the thin film transistor.
Implementation Method 1
the first gate electrode shields light entering the semiconductor layer from below, and the second gate electrode shields light entering the semiconductor layer from above
Data Source
AI summary
Provided is a thin film transistor including: a first gate electrode; a first gate insulating layer covering the first gate electrode; a semiconductor layer on the first gate insulating layer; a second gate insulating layer on the semiconductor layer; a second gate electrode on the second gate insulating layer; and a drain electrode and a source electrode electrically connected to the semiconductor layer, in which: the semiconductor layer is an amorphous oxide semiconductor containing at least one of Zn, Ga, In, and Sn; the first gate electrode shields light entering the semiconductor layer from below, and the second gate electrode shields light entering the semiconductor layer from above; and the second gate electrode is electrically connected to the first gate electrode by penetrating the first gate insulating layer and the second gate insulating layer, to thereby shield light entering the semiconductor layer from at least one of sides thereof.