Polysilicon TFT Pixel Structure With Integrated PN Photodiode
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Solution Overview
Problem
Conventional medical amorphous silicon panel detectors have issues with thickness, optical path interference, larger occupied area, lower resolution, and higher production costs due to separate fabrication of thin film transistors and photodiodes, leading to inefficiencies in light detection.
Innovation Solution
A display panel design featuring a polysilicon thin film transistor with a PN structure formed by ion implantation, where the polysilicon layer includes doped regions to create a TFT and amorphous silicon photodiode simultaneously, reducing complexity and increasing efficiency in light detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If separate fabrication of thin film transistor and amorphous silicon photodiode is used, then device functionality is achieved, but manufacturing complexity and production cost increase
Solution Approach 1:
The patent combines the thin film transistor and amorphous silicon photodiode into a single integrated pixel unit structure. The polysilicon layer serves dual purposes: as the transistor channel layer and as the photodiode light-sensitive layer. This merging eliminates separate fabrication processes for the two components, reducing manufacturing complexity and production cost while maintaining both transistor switching functionality and photodiode light detection capability within the same device structure
2Manufacturing precision
If intermediate layer with light doping is used in amorphous silicon photodiode, then photodiode structure is formed, but panel detector thickness increases
Solution Approach 1:
The patent merges the transistor channel layer and photodiode light-sensitive layer into a single polysilicon layer. By forming both structures simultaneously from the same layer through selective doping regions, the need for a separate intermediate layer with light doping is eliminated. This integration maintains precise photodiode structure formation while significantly reducing the overall panel detector thickness
Solution Approach 2:
The patent changes the doping parameters within the polysilicon layer to create different functional regions. By applying different doping concentrations and types to specific regions of the polysilicon layer, the transistor channel and photodiode light-sensitive regions are differentiated without requiring additional layers. This parameter-based differentiation achieves precise structure formation while minimizing thickness
3Length of stationary object
If thin intermediate layer is used in amorphous silicon photodiode, then panel detector thickness is reduced, but optical path interference between adjacent pixel units increases
Solution Approach 1:
The patent integrates the transistor and photodiode functions into a single polysilicon layer structure, which allows for optimized optical path design. The unified structure enables better control over light interaction, reducing stray light and optical interference between adjacent pixel units while maintaining thin profile. The integrated design allows for more efficient light collection and reduced optical path length within the active detection region
4Measurement precision
If thin film transistor and amorphous silicon photodiode are disposed separately, then device functionality is achieved, but occupied area increases and resolution decreases
Solution Approach 1:
The patent merges the thin film transistor and amorphous silicon photodiode into a single integrated pixel unit with shared polysilicon layer. This integration eliminates the need for separate disposal of the two components, significantly reducing the occupied area per pixel unit. The compact integrated structure enables higher pixel density and improved display resolution while maintaining complete device functionality for both switching and light detection operations
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 approach results in a thinner, more efficient display panel with improved resolution and lower production costs by integrating the TFT and amorphous silicon photodiode fabrication, enhancing signal-to-noise ratio and reducing interference.
Implementation Method 1
a polysilicon thin film transistor with a PN structure formed by ion implantation
Data Source
AI summary
Display panels are provided. The display panel includes a substrate and a thin film transistor (TFT) disposed on the substrate. The TFT includes a polysilicon layer, a gate layer, and a source-drain contacting layer. The polysilicon layer includes a first portion corresponding to the gate layer, two second portions disposed on two opposite sides of the first portion, two third portions disposed on two outer sides of the two second portions away from the first portion, and a fourth portion. The fourth portion is disposed on one of the two third portions to define a PN structure therebetween. The source-drain contacting layer is disposed on the gate layer and electrically contacts the fourth portion and the two third portions.