Oxide Semiconductor Layer Defect Evaluation via Photoconductivity
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Solution Overview
Problem
Transistors with high trap state densities in semiconductor layers exhibit unstable electrical characteristics, leading to low reliability and malfunction in semiconductor devices, and existing methods for evaluating defect density are limited and inaccurate.
Innovation Solution
A semiconductor device with an oxide semiconductor layer is used, where the layer is irradiated with light of specific wavelengths and intensities to evaluate defect density by measuring current changes over time, and an insulating film with lower electron affinity is employed to enhance channel formation and reduce trap states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a semiconductor layer with high trap state density is used, then the device can be manufactured more easily, but the electrical characteristics become unstable and reliability decreases
Solution Approach 1:
The invention changes the material composition parameters of the semiconductor layer by introducing specific metal elements (such as In, Ga, Zn) in controlled ratios to form oxide semiconductor layers with optimized electrical properties. This allows achieving low trap state density while maintaining manufacturability through sputtering deposition processes.
Solution Approach 2:
The invention uses composite oxide semiconductor materials containing multiple metal elements (e.g., In-Ga-Zn-O) to achieve superior electrical characteristics. The composite structure allows tuning of band gap, carrier mobility, and trap state density by adjusting the proportion of constituent elements, thereby improving reliability without sacrificing ease of manufacture.
2Device complexity
If existing evaluation methods are used, then the evaluation process is simple, but the measurement precision of defect density is limited and inaccurate
Solution Approach 1:
The invention replaces conventional electrical measurement methods with photoelectric characterization techniques. By measuring optical absorption spectra and photo-induced current characteristics, the method achieves precise defect density evaluation without requiring complex mechanical or electrical test structures.
Solution Approach 2:
The invention utilizes optical absorption characteristics (color changes) of the semiconductor material to evaluate defect density. By analyzing absorption spectra at different wavelengths, particularly in the UV-visible range, the method precisely determines defect states and carrier concentrations without complex measurement apparatus.
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 method provides a semiconductor layer with low trap state density, resulting in stable electrical characteristics and high field-effect mobility, while also enabling accurate evaluation of defect density, thus improving the reliability of semiconductor devices.
Implementation Method 1
the layer is irradiated with light of specific wavelengths and intensities to evaluate defect density by measuring current changes over time
Data Source
AI summary
A semiconductor layer with a low density of trap states is provided. A transistor with stable electrical characteristics is provided. A transistor having high field-effect mobility is provided. A semiconductor device including the transistor is provided. A method for evaluating a semiconductor layer is provided. A method for evaluating a transistor is provided. A method for evaluating a semiconductor device is provided. Provided is, for example, a semiconductor layer with a low defect density which can be used for a channel formation region of a transistor, a transistor including a semiconductor layer with a low defect density in a channel formation region, or a semiconductor device including the transistor.