Oxide TFT Carrier Control Layer for High-Temperature Threshold Stability
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Solution Overview
Problem
Oxide semiconductor thin film transistors experience reduced reliability and stability at high temperatures due to variations in threshold voltage and Fermi energy level caused by temperature changes.
Innovation Solution
Incorporating a carrier control layer made of an oxide semiconductor material and an element from group 15 of the periodic table, such as phosphorus, arsenic, or bismuth, to trap excited electrons and stabilize the Fermi energy level, thereby maintaining threshold voltage stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxide semiconductor thin film transistor is used, then manufacturing cost is reduced and transparency is improved, but reliability decreases at high temperature
Solution Approach 1:
The active layer is divided into two distinct layers: a main active layer (first oxide semiconductor layer) and a carrier control layer (second oxide semiconductor layer). This segmentation allows each layer to perform its specific function - the main active layer provides the primary conduction path while the carrier control layer specifically manages carrier concentration and traps excited electrons, thereby resolving the threshold voltage instability at high temperatures
Solution Approach 2:
The carrier control layer acts as an intermediary between the gate electrode and the main active layer. It mediates the interaction by controlling carrier injection into the main active layer and trapping excited electrons, thus stabilizing the Fermi energy level and threshold voltage under high temperature conditions without affecting the overall transistor structure or manufacturing process
2Manufacturing precision
If oxide semiconductor thin film transistor is used, then manufacturing temperature is reduced, but threshold voltage changes at high temperature
Solution Approach 1:
The carrier control layer is designed with specific material composition (oxide semiconductor with group 15 elements such as phosphorus, arsenic, or bismuth) and controlled thickness (1-10 nm) to optimize its electron trapping capability. By adjusting these parameters, the layer effectively stabilizes the Fermi energy level at high temperatures while maintaining compatibility with low-temperature manufacturing processes
3Reliability
If carrier control layer is added, then threshold voltage stability is improved, but device complexity increases
Solution Approach 1:
The carrier control layer is integrated with the main active layer to form a unified active layer structure. Both layers are made of oxide semiconductor materials and can be deposited in a single manufacturing process sequence, merging the carrier control function with the active layer structure rather than adding a separate, complex component
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 carrier control layer effectively traps electrons with high volatility, ensuring temperature stability and improved driving stability and reliability of the thin film transistor, even under high temperature conditions.
Implementation Method 1
the carrier control layer includes an oxide semiconductor material and an element of group 15 of periodic table... capable of trapping excited electrons in a channel portion
Data Source
AI summary
A thin film transistor and a display apparatus including the thin film transistor are provided. The thin film transistor includes an active layer on a substrate and a gate electrode that is spaced apart from the active layer and overlaps at least a part of the active layer, wherein the active layer includes a main active layer and a carrier control contacting the main active layer, and wherein the carrier control layer includes an oxide semiconductor material and an element of group 15 of periodic table.