Photoelectric Transistor Active Layer Layout for Light Absorption
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Solution Overview
Problem
Existing transistors with planar active layers fail to simultaneously optimize electrical performance and photoelectric induction capability, as thin active layers allow insufficient light absorption while thick layers lead to electrical performance degradation due to weakened gate control.
Innovation Solution
A transistor design featuring an active layer with a first active portion of greater thickness and second and third active portions of thinner thickness, positioned on either side of the first portion, enhancing light absorption and maintaining electrical performance by ensuring adequate gate modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the active layer thickness is increased to improve light absorption, then photoelectric induction capability is improved, but electrical performance deteriorates due to gate modulation capability reduction
Solution Approach 1:
The active layer is divided into multiple segments with different thicknesses: a first active layer portion with greater thickness for light absorption, and second/third active layer portions with smaller thicknesses for electrical performance. This segmentation allows each portion to optimize for its specific function, resolving the contradiction between light absorption and electrical performance.
Solution Approach 2:
Different regions of the active layer are assigned different thickness characteristics: the first active layer portion has increased thickness locally to enhance light absorption, while the second and third portions maintain smaller thicknesses to ensure proper gate modulation. This local quality differentiation enables simultaneous optimization of both photoelectric and electrical properties.
2Productivity
If the active layer is made thicker to enhance photoelectric sensing, then photocurrent increases, but off-state current increases due to back channel formation
Solution Approach 1:
The active layer is segmented into thickness zones where the first portion (thicker) generates higher photocurrent, while the second and third portions (thinner) prevent back channel formation and reduce off-state current. This segmentation decouples the photocurrent generation function from the off-state current control function.
Solution Approach 2:
The patent converts the potential harm of thick active layer (back channel formation) into benefit by strategically placing thinner portions at critical locations (second and third portions) where gate modulation is needed, while maintaining thicker portions (first portion) where light absorption is prioritized. The thinner portions act as barriers that prevent the harmful back channel effect.
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
This design increases light absorption and photoelectric induction capability while ensuring normal on-off switching characteristics, addressing the limitations of planar active layers in both electrical and photoelectric performance.
Implementation Method 1
when an energy of a single photon of incident light is greater than a band gap of a semiconductor material, the semiconductor material will absorb the photon energy and generate an electron-hole pair to increase the concentration of carriers
Data Source
AI summary
Provided are a transistor and a photoelectric sensor, the transistor includes a substrate and an active layer located on a side of the substrate; the active layer includes a source region, a drain region and a channel region located between the source region and the drain region, and in the channel region, the active layer includes a first active portion, a second active portion and a third active portion, the second active portion and the third active portion are respectively located on two opposite sides of the first active portion in a first direction, the second active portion is communicated with the source region in the active layer, and the third active portion is communicated with the drain region in the active layer.