Oxide Semiconductor Thin-Film Transistor Light Stability via Rare-Earth Doping
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Solution Overview
Problem
Current oxide semiconductor thin-film transistors suffer from light-induced instability due to oxygen vacancies, leading to threshold voltage shifts under irradiation, which affects display performance, and existing solutions either compromise mobility or increase production complexity and cost.
Innovation Solution
Doping rare-earth oxides such as praseodymium, terbium, dysprosium, or ytterbium into metal oxide semiconductors to act as light stabilizers, shifting the band structure from direct to indirect gap, reducing photo-induced carriers and maintaining threshold voltage stability under light irradiation without degrading mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oxygen vacancy concentration is decreased by doping material with strong binding strength with oxygen, then light-induced stability is improved, but mobility is decreased
Solution Approach 1:
The patent changes the chemical composition parameters by introducing rare-earth elements (Pr, Tb, Dy, Yb) at specific concentration ranges (0.01-0.2 mole ratio) to modify the band structure from direct to indirect gap, reducing photo-induced carrier generation while maintaining acceptable mobility
Solution Approach 2:
The patent creates composite oxide semiconductor materials by combining metal oxides (In, Zn, Ga, Sn, Si, Al, Mg, Zr, Hf, or Ta) with rare-earth oxides (Pr, Tb, Dy, Yb), forming a composite structure that leverages the oxygen-binding capability of rare-earth elements while maintaining the electrical transport properties of the metal oxide matrix
2Reliability
If light shield is introduced to improve light-response characteristics, then light-induced stability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent extracts the light-shielding function from a separate structural component (black matrix) and integrates it into the channel layer material itself through rare-earth element doping, eliminating the need for additional shield structures and simplifying the fabrication process
Solution Approach 2:
The rare-earth doped oxide semiconductor serves multiple functions simultaneously: it acts as the charge transport channel while also providing intrinsic light-shielding properties through the indirect band gap structure, combining electrical and optical functions in a single material layer
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 approach significantly enhances light-induced stability with negligible impact on mobility and other performance parameters, improving the reliability of oxide semiconductor thin-film transistors while maintaining simple and cost-effective fabrication processes.
Implementation Method 1
shifting the band structure from direct to indirect gap, reducing photo-induced carriers
Implementation Method 2
The sub-gap states will be excited and release electron hole pairs under irradiation with certain energy
Data Source
AI summary
The present application discloses an oxide semiconductor thin-film and a thin-film transistor consisted thereof. The oxide semiconductor thin-film is fabricated by doping a certain amount of rare-earth oxide (RO) as light stabilizer to metal oxide (MO) semiconductor. The thin-film transistor comprising a gate electrode, a channel layer consisted by the oxide semiconductor thin-film, a source and drain electrode; the thin-film transistor employing etch-stop structure, a back-channel etch structure or a top-gate self-alignment structure.