Thin-Film Transistor Edge-Region Control to Eliminate Hump Effect
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Solution Overview
Problem
Thin film transistors experience a hump effect due to early turn-on of the edge region, leading to instability and sub-threshold performance issues, as voltage easily gathers at the edge region, causing inversion charges to be generated before the threshold voltage is reached, affecting the performance of electronic devices.
Innovation Solution
Incorporating an auxiliary layer that overlaps with the edge region of the channel region, adjusting the work function difference between the gate electrode and active layer materials to enhance the turn-on voltage of the edge region, ensuring synchronous turn-on with the main region, thereby alleviating or eliminating the hump effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thin film transistor uses a conventional structure without auxiliary layer, then the device complexity is low, but the edge region turns on early causing hump effect and performance instability
Solution Approach 1:
The gate electrode structure is segmented into a main gate electrode and an auxiliary gate electrode. The auxiliary gate electrode is positioned to overlap with the edge region of the channel region, allowing independent control of the edge region's turn-on voltage. This segmentation enables the auxiliary gate to compensate for the early turn-on effect in the edge region, thereby improving performance stability without excessively complicating the overall device structure.
Solution Approach 2:
The auxiliary gate electrode is specifically positioned to overlap with the edge region of the channel region, creating a localized electric field that selectively adjusts the turn-on voltage of the edge region. This local quality approach allows precise control over the edge region's electrical characteristics, ensuring synchronous turn-on with the main region and eliminating the hump effect while maintaining simplicity in other areas of the device.
2Reliability
If the turn-on voltage of the edge region is not enhanced, then the manufacturing process is simple, but voltage gathers at the edge region causing inversion charges to be generated before threshold voltage is reached
Solution Approach 1:
The auxiliary gate electrode is formed in advance during the manufacturing process, positioned to overlap with the edge region of the channel region. This preliminary action enables the auxiliary gate to pre-establish the necessary electric field configuration that will control the turn-on voltage of the edge region during device operation, ensuring proper threshold voltage control without requiring additional complex manufacturing steps later in the process.
Data Source
AI summary
A thin film transistor includes a substrate, and a gate electrode, a gate insulating layer, an active layer, a source electrode and a drain electrode which are on the substrate. The active layer includes a channel region between the source electrode and the drain electrode and the channel region includes an edge region along a channel length direction and a main region outside the edge region. The thin film transistor further includes an auxiliary layer, a projection of the auxiliary layer on the substrate is at least partially overlapped with a projection of the edge region of the channel region on the substrate, and the auxiliary layer is configured to enhance a turn-on voltage of the edge region of the channel region.