Photosensor Linear Response via Interface Dielectric Layer
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Solution Overview
Problem
Ambient light sensors using amorphous silicon or poly silicon materials exhibit non-linear photo current output in response to light illumination, leading to inaccurate readings and operational errors due to the sensitivity of these materials to visible and near-infrared light.
Innovation Solution
A photosensor structure comprising a metal conductive layer, an interface dielectric layer, a silicon-rich dielectric layer, and a transparent conductive layer, where the interface dielectric layer is formed using plasma surface treatment to enhance the linear relationship between photo current and light intensity, thereby improving precision and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If amorphous silicon or poly silicon is used as the photosensor material, then the sensitivity to visible and near-infrared light is improved, but the linearity between photo current and light illumination deteriorates
Solution Approach 1:
An interface dielectric layer is introduced between the metal conductive layer and the silicon-rich dielectric layer. This interface layer acts as a mediator that prevents direct contact between the metal and silicon-rich dielectric, thereby eliminating the non-linear photo current effect while preserving the high sensitivity of the silicon-rich material to visible and near-infrared light.
Solution Approach 2:
The harmful direct interface between metal conductive layer and silicon-rich dielectric layer is extracted or removed by inserting an intermediate dielectric layer. This extraction eliminates the source of non-linearity (the direct metal-silicon interface) while maintaining the beneficial optical properties of the silicon-rich layer.
2Ease of manufacture
If low temperature deposition process is used to form silicon-rich oxide layer, then the manufacturing complexity is reduced, but the photo current linearity deteriorates
Solution Approach 1:
The interface dielectric layer serves as a mediator that resolves the conflict between using simple low-temperature deposition processes and achieving linear photo current output. By inserting this intermediate layer, the patent enables the use of straightforward deposition techniques while eliminating the non-linearity that would otherwise result from direct metal-silicon contact.
3Device complexity
If silicon-rich dielectric layer is formed directly on metal conductive layer, then the device complexity is reduced, but the measurement precision deteriorates
Solution Approach 1:
An interface dielectric layer is inserted between the metal conductive layer and silicon-rich dielectric layer to prevent direct contact. This additional layer improves measurement precision by eliminating non-linear photo current effects, while the overall device complexity remains manageable due to the simplicity of the deposition processes required.
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 proposed structure ensures a linear relationship between photo current and light intensity, enhancing the precision and stability of the photosensor, allowing for accurate light illumination measurements and maintaining steady photoelectric efficiency over time.
Implementation Method 1
the interface dielectric layer is formed using plasma surface treatment to enhance the linear relationship between photo current and light intensity
Implementation Method 2
when the light having a specific illumination illuminates the photosensor and the corresponding photo current is then measured
Data Source
AI summary
A photosensor includes a metal conductive layer, an interface dielectric layer, a silicon-rich dielectric layer and a transparent conductive layer. The interface dielectric layer is formed on the metal conductive layer. The silicon-rich dielectric layer is formed on the interface dielectric layer. The transparent conductive layer is formed on the silicon-rich dielectric layer. A method for fabricating a photosensor is also disclosed herein.