Quantum Dot Photoelectric Conversion Layer for Noise Reduction
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Solution Overview
Problem
Metal insulator semiconductor (MIS) photoelectric conversion devices suffer from noise due to defect energy levels in the photoelectric conversion film, leading to dark current and incomplete depletion, which results in noise in the output signal.
Innovation Solution
Incorporating a photoelectric conversion layer with quantum dots of 1 nm to 20 nm in size, which reduces lattice defects and noise by accumulating and discharging electric charge effectively, and using specific materials like PbS, PbSe, or CdSe for the quantum dots and a semiconductor material for the quantum-dot-disposed member to enhance sensitivity and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional photoelectric conversion film is used, then the device structure is simple, but noise increases due to defect energy levels and dark current
Solution Approach 1:
The photoelectric conversion layer uses a composite structure combining quantum dots (PbS, PbSe, or CdSe) dispersed in a semiconductor material matrix (a-Si, μc-Si, or GaAs). This composite approach reduces defect energy levels and dark current while maintaining photoelectric conversion functionality, resolving the contradiction between noise reduction and structural complexity.
Solution Approach 2:
The invention changes the physical parameters of the photoelectric conversion layer by using quantum dots with specific size ranges (1-20 nm) and controlling their dispersion in the semiconductor matrix. This parameter optimization reduces lattice defects and noise while achieving effective charge accumulation, addressing the contradiction between reliability improvement and device complexity.
2Measurement precision
If quantum dots are incorporated into the photoelectric conversion layer, then sensitivity and noise reduction improve, but manufacturing complexity increases
Solution Approach 1:
By specifying quantum dot size parameters (1-20 nm) and material composition ratios, the invention optimizes sensitivity while providing clear manufacturing guidelines. The use of established semiconductor materials as the matrix simplifies the fabrication process despite the addition of quantum dots.
Solution Approach 2:
The semiconductor material matrix acts as an intermediary that holds and disperses quantum dots, enabling sensitivity enhancement through quantum dots while maintaining manufacturability through the use of conventional semiconductor processing techniques for the matrix material.
3Measurement precision
If the photoelectric conversion layer uses high optical absorption coefficient materials, then sensitivity increases, but defect energy levels and noise increase
Solution Approach 1:
The composite structure of quantum dots in a semiconductor matrix provides high optical absorption (sensitivity) through the quantum dots while the semiconductor matrix provides a clean energy band structure that minimizes defect energy levels and dark current, resolving the contradiction between sensitivity and noise.
Solution Approach 2:
The invention applies local quality by using quantum dots specifically for light absorption (high optical coefficient) while the surrounding semiconductor matrix provides the clean electronic environment. Each material performs its optimal function locally, achieving both high sensitivity and low noise.
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 configuration significantly reduces noise by minimizing defect energy levels and improving sensitivity, allowing for more efficient accumulation and discharge of electric charge, thereby enhancing the signal quality in photoelectric conversion devices.
Implementation Method 1
a photoelectric conversion layer disposed between the first electrode and the second electrode, wherein the photoelectric conversion layer includes quantum dots
Data Source
AI summary
A photoelectric conversion device according to an exemplary embodiment includes a pixel which includes a photoelectric conversion unit and an amplifier transistor configured to output a signal generated by the photoelectric conversion unit. The photoelectric conversion unit includes a first electrode, a second electrode electrically connected to the amplifier transistor, a photoelectric conversion layer, and an insulating layer disposed between the photoelectric conversion layer and the second electrode. The photoelectric conversion layer includes quantum dots.