Nitrogen-Gradient Oxide Semiconductor Layer for TFT Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-mobility oxide semiconductor layers in thin film transistors (TFTs) are prone to becoming conductive due to their thickness, leading to instability and damage during the patterning process, which affects the reliability and performance of TFTs in display apparatuses.
Innovation Solution
A TFT structure is developed with a supporting layer containing nitrogen, where a first oxide semiconductor layer with 1-5% nitrogen concentration supports a second oxide semiconductor layer, and both layers have a gradient nitrogen concentration, ensuring the second layer remains non-conductive and stable even at thicknesses above 10 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the oxide semiconductor layer thickness is increased above 10 nm, then the layer provides sufficient coverage and stability, but the layer becomes conductive due to high carrier concentration
Solution Approach 1:
The thick oxide semiconductor layer is segmented into two functional zones with different nitrogen concentrations. The first layer can be thicker (providing structural stability) while the second layer remains thin enough or has sufficiently low nitrogen concentration to avoid becoming conductive, even when the total thickness exceeds 10 nm.
Solution Approach 2:
The nitrogen concentration is varied locally through the thickness of the oxide semiconductor layer. The region closer to the substrate has higher nitrogen for stability, while the region closer to the gate electrode has lower nitrogen to maintain semiconductor characteristics, allowing the overall structure to be thick without becoming conductive.
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 TFTs exhibit improved stability and reliability, with the nitrogen gradient in the oxide semiconductor layers preventing conductive characteristics and enhancing film stability, thus ensuring excellent display characteristics and reliability in display apparatuses.
Implementation Method 1
the first oxide semiconductor layer includes nitrogen of 1 at % to 5 at % concentration with respect to number of atoms
Implementation Method 2
the second oxide semiconductor layer has a nitrogen concentration which is lower than a nitrogen concentration of the first oxide semiconductor layer and a gradient of the nitrogen concentration such that the nitrogen concentration is lowered in a direction closer to the gate electrode
Data Source
AI summary
A thin film transistor is provided. The thin film transistor includes an oxide semiconductor layer on a substrate, a gate electrode insulated from the oxide semiconductor layer to overlap at least a portion of the oxide semiconductor layer, a source electrode connected to the oxide semiconductor layer, and a drain electrode spaced apart from the source electrode and connected to the oxide semiconductor layer. The oxide semiconductor layer includes a first oxide semiconductor layer on the substrate and a second oxide semiconductor layer on the first oxide semiconductor layer, the first oxide semiconductor layer includes nitrogen of 1 at % to 5 at % concentration with respect to number of atoms, and the second oxide semiconductor layer has a nitrogen concentration which is lower than a nitrogen concentration of the first oxide semiconductor layer and a gradient of the nitrogen concentration such that the nitrogen concentration is lowered in a direction closer to the gate electrode.