Thin Film Transistor Driving Stability via Dual Gate Segmentation
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Solution Overview
Problem
In organic light emitting display devices, the driving stability of driving transistors is reduced due to external noise affecting the active layer, leading to increased drain-source current with increasing drain-source voltage, especially in top gate structures where the bottom gate electrode is not effectively connected to the source electrode.
Innovation Solution
A thin film transistor design is implemented with a N-type semiconductor layer, a P-type semiconductor layer, a first gate electrode, a gate insulation layer, a source electrode connected to the P-type semiconductor layer, and a drain electrode connected to the P-type semiconductor layer, without connecting the source electrode to the bottom gate electrode, enhancing driving stability by maintaining constant drain-source current across varying voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a top gate structure is used in the driving transistor, then the device area is reduced and manufacturing is simplified, but the driving stability deteriorates due to external noise affecting the active layer
Solution Approach 1:
The transistor is divided into two separate gates: a bottom gate electrode and a top gate electrode. The bottom gate electrode is positioned to overlap the active layer and connected to the source electrode, while the top gate electrode is positioned above the P-type semiconductor layer. This segmentation allows each gate to perform distinct functions in controlling the channel, with the bottom gate providing noise immunity and the top gate enabling standard manufacturing processes.
2Reliability
If the bottom gate electrode is connected to the source electrode to improve driving stability, then the transistor area increases and additional contact hole processes are required
Solution Approach 1:
The bottom gate electrode and source electrode are electrically connected by positioning the bottom gate electrode to overlap the active layer and extending it to contact the source electrode region. This merging of functions allows the bottom gate to serve both as a gate control element and as part of the source electrode structure, eliminating the need for separate contact holes while maintaining driving stability.
3Reliability
If the bottom gate electrode is positioned to overlap the active layer, then the transistor area increases, but the driving stability improves
Solution Approach 1:
The bottom gate electrode is positioned to overlap only the active layer region where it is needed for noise immunity, rather than extending across the entire transistor structure. The top gate electrode then provides the primary gate control function above the P-type semiconductor layer. This localized positioning minimizes the area increase while maintaining the driving stability benefits.
Data Source
AI summary
Disclosed are a thin film transistor, a method of manufacturing the same, and an organic light emitting display device including the same, in which a driving stability of a driving transistor is enhanced even without connecting a source electrode to a bottom gate electrode of the driving transistor. The film transistor includes a N-type semiconductor layer, a P-type semiconductor layer on the N-type semiconductor layer, a first gate electrode on the P-type semiconductor layer, a gate insulation layer between the first gate electrode and the P-type semiconductor layer, a first source electrode connected to a first side of the P-type semiconductor layer, and a first drain electrode connected to a second side of the P-type semiconductor layer.