PIN Diode Layer Segmentation for Digital X-ray Detector Leakage Current
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Solution Overview
Problem
Digital X-ray detector devices face challenges in minimizing leakage current and light transmittance reduction in PIN diodes, which affect image clarity and efficiency.
Innovation Solution
A thin film transistor array substrate with a PIN diode structure that includes a p+ type semiconductor layer, a p− type semiconductor layer, an intrinsic semiconductor layer, an n− type semiconductor layer, and an n+ type semiconductor layer, where the p− type and n− type layers have lower impurity concentrations and specific thicknesses to minimize leakage current and maintain light transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a PIN diode structure is used in digital X-ray detector, then light detection capability is improved, but leakage current is generated affecting image clarity
Solution Approach 1:
The PIN diode is segmented into five distinct semiconductor layers (p+, p-, intrinsic, n-, n+) with different impurity concentrations. This segmentation allows each layer to perform specific functions: the p+ and n+ layers provide high conductivity contacts, the p- and n- layers with lower impurity concentrations reduce leakage current, and the intrinsic layer enables light detection. By dividing the diode into functional segments, the patent achieves both high detection capability and low leakage current.
Solution Approach 2:
Different regions of the PIN diode are assigned different impurity concentrations tailored to their specific functions. The p+ and n+ layers have high impurity concentrations for efficient charge collection, while the p- and n- layers have lower impurity concentrations to minimize leakage current. The intrinsic layer has no impurities to enable photoelectric conversion. This local optimization of material properties resolves the contradiction between detection capability and leakage current.
2Object-generated harmful factors
If impurity concentration in semiconductor layers is increased to reduce leakage current, then leakage current is minimized, but light transmittance is reduced
Solution Approach 1:
The patent applies different impurity concentrations to different layers based on their functional requirements. The p- and n- layers use lower impurity concentrations to maintain light transmittance while still providing sufficient conductivity to minimize leakage current. The p+ and n+ layers use high impurity concentrations only where needed for electrode contacts. This localized optimization allows the system to achieve low leakage current without sacrificing overall light transmittance.
Solution Approach 2:
The semiconductor structure is divided into multiple layers with graded impurity concentrations. By segmenting the diode into p+, p-, intrinsic, n-, and n+ layers, the patent creates a gradient of impurity concentrations that balances leakage current reduction with light transmittance maintenance. The lower impurity concentration layers (p- and n-) are positioned where light transmission is critical, while high impurity concentration layers (p+ and n+) are positioned at contacts where conductivity is paramount.
3Ease of manufacture
If conventional film printing scheme is used for X-ray detection, then image storage is simple, but checking results takes long time and film preservation is difficult
Solution Approach 1:
The patent replaces the mechanical film printing system with an electronic digital detection system using PIN diodes and thin film transistors. Instead of using physical film that requires printing and manual review, the system converts X-ray signals into electrical signals that are processed and displayed electronically. This substitution eliminates the time delay associated with film development and printing, enabling real-time image review while also solving film preservation issues through digital storage.
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 solution effectively reduces leakage current and maintains light transmittance, resulting in clearer and more accurate X-ray images by preventing the ejection of holes and electrons, thereby enhancing the digital X-ray detector's performance.
Implementation Method 1
The digital X-ray detector device detects the transmittance of the X-ray transmitted through the object
Implementation Method 2
A digital X-ray detector device using a thin film transistor has been developed
Data Source
AI summary
A thin film transistor array substrate for a digital X-ray detector device includes a p+ type semiconductor layer and a p− type semiconductor layer having different impurity concentrations are disposed above an intrinsic semiconductor layer of the PIN diode and an n+ type semiconductor layer and an n− type semiconductor layer having different impurity concentrations are disposed below the intrinsic semiconductor layer of the PIN diode to minimize ejection of holes by the p− type semiconductor layer and minimize ejection of electros by the n− type semiconductor layer, thereby minimizing occurrence of leakage current of the PIN diode.