Thin Film Transistor Light-Shielding Layer Leakage Current
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Solution Overview
Problem
Conventional Thin Film Transistors (TFTs) generate leakage currents due to light irradiation of the semiconductor active layer, particularly in top-gate configurations where backlight can pass through and affect the semiconductor active layer, causing conductive passages between the drain and source electrodes.
Innovation Solution
Incorporating a light-shielding layer between the source and drain electrodes, positioned on the side of the semiconductor active layer further away from the gate electrode, which blocks incident light from irradiating the semiconductor active layer, thereby preventing leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a top-gate TFT configuration is used to prevent ambient light from affecting the semiconductor active layer, then the gate electrode can block ambient light, but the backlight can pass through and irradiate the semiconductor active layer causing leakage current
Solution Approach 1:
The light-shielding function is segmented from the gate electrode and implemented as a separate light-shielding layer positioned between the source/drain electrodes. This segmentation allows the gate electrode to focus on electrical control while the dedicated light-shielding layer handles backlight blocking, resolving the contradiction between ambient light protection and backlight interference prevention.
Solution Approach 2:
A light-shielding layer is introduced as an intermediary component between the source/drain electrodes and the semiconductor active layer. This intermediary layer specifically blocks backlight from reaching the semiconductor active layer while not interfering with the gate electrode's ability to control the transistor, thereby eliminating leakage current without compromising electrical performance.
2Object-affected harmful factors
If a protection layer is disposed above the semiconductor active layer to prevent water and oxygen from affecting the metal oxide semiconductor, then the semiconductor active layer is protected from environmental factors, but the non-metal protection layer causes the TFT to generate leakage current
Solution Approach 1:
The light-shielding function is extracted from the protection layer and implemented as a separate light-shielding layer made of metal material. This extraction allows the protection layer to focus solely on preventing water and oxygen ingress, while the dedicated light-shielding layer made of metal (rather than non-metal) provides both light blocking and electrical stability, eliminating the leakage current issue.
Solution Approach 2:
The material parameter of the light-shielding layer is changed from non-metal to metal. This parameter change fundamentally alters the electrical properties, transforming the component from a source of leakage current to a component that provides both optical shielding and electrical stability, thereby resolving the contradiction between environmental protection and electrical performance.
3Use of energy by moving object
If the semiconductor active layer is irradiated by backlight, then the TFT can operate with light transmission, but the irradiation causes the semiconductor active layer to generate a conductive passage between drain and source electrodes resulting in leakage current
Solution Approach 1:
The light-shielding property is applied locally and selectively to specific regions where it is needed. The light-shielding layer is positioned between the source/drain electrodes to block backlight from reaching the semiconductor active layer in those specific areas, while allowing light transmission in other regions where it is needed for display operation. This local application of light shielding resolves the contradiction between light transmission and leakage prevention.
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 implementation of a light-shielding layer between the source and drain electrodes effectively shields the semiconductor active layer from light, resulting in a TFT with highly stable properties and reduced leakage current generation.
Implementation Method 1
the light-shielding layer is disposed on a side of the semiconductor active layer which is further away from the gate electrode... configured for blocking the incident light from irradiating the semiconductor active layer
Data Source
AI summary
A thin film transistor (TFT), a method for fabricating the same, an array substrate and a display device are provided. The TFT includes a source electrode and a drain electrode, a semiconductor active layer, a gate insulating layer and a gate electrode. The TFT further includes a light-shielding layer between the source electrode and the drain electrode. The light-shielding layer separates the source electrode and the drain electrode, and the light-shielding layer is disposed on a light incident side of the semiconductor active layer and is used to prevent the incident light from irradiating on the semiconductor active layer.