Graphene Schottky Junction Detector Dark Current Control
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Solution Overview
Problem
Electromagnetic wave detectors with graphene field effect transistors face challenges in reducing variations in dark current due to foreign matter like moisture or resist at the junction interface, leading to increased leakage currents and insufficient reduction of dark current variations across detectors.
Innovation Solution
The design incorporates a semiconductor substrate with a first insulating film, a two-dimensional material layer forming a Schottky junction, a second electrode in contact with the substrate, and a control electrode around the junction to form a second Schottky junction, reducing dark current variations by connecting the depletion layers and preventing foreign matter accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If graphene is used as the detection layer in an electromagnetic wave detector, then the mobility and detection capability are improved, but the dark current becomes large due to zero or minute band gap
Solution Approach 1:
An insulating film is introduced as an intermediary layer between the graphene detection layer and the silicon substrate. This mediator enables the formation of a Schottky junction that effectively reduces dark current while preserving the high mobility and detection capability of graphene. The insulating film thickness is controlled at 2-10 nm to achieve optimal electrical isolation and junction formation.
Solution Approach 2:
The electrical properties at the graphene-substrate interface are modified by changing the physical parameters of the insulating film layer. By controlling the film thickness (2-10 nm) and material composition, the Schottky barrier height and width are optimized to reduce dark current while maintaining detector sensitivity.
2Object-generated harmful factors
If graphene is placed in direct contact with the silicon substrate to reduce dark current, then the dark current is reduced, but foreign matter such as moisture or resist remains at the junction interface causing leakage current and variations in dark current
Solution Approach 1:
The insulating film serves as a mediator that physically separates graphene from the silicon substrate, creating a controlled interface that prevents foreign matter accumulation. This intermediary layer eliminates the direct contact problem while maintaining the desired electrical characteristics through Schottky junction formation.
Solution Approach 2:
The insulating film is used as a sacrificial or temporary structure during manufacturing that can be precisely controlled and removed or retained as needed. This disposable-like approach allows for clean interface formation without the complications of direct graphene-substrate contact.
3Reliability
If the insulating film is made thinner to improve electrical contact, then the Schottky junction effectiveness is improved, but the risk of foreign matter contamination increases
Solution Approach 1:
The insulating film thickness is optimized to a specific range (2-10 nm) that balances electrical performance and contamination resistance. This parameter optimization ensures the Schottky junction is effective while the film remains thick enough to prevent foreign matter penetration and contamination.
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 configuration effectively reduces dark current variations and enhances detection sensitivity by amplifying photocurrent while maintaining low dark current levels, improving the manufacturing yield of electromagnetic wave detector arrays.
Implementation Method 1
a two-dimensional material layer 5 having a joint part 12 forming a Schottky junction with the semiconductor substrate 1
Implementation Method 2
a control electrode 7 disposed at least partly around the joint part 12 in plan view to form a Schottky junction with the semiconductor substrate 1
Data Source
AI summary
An electromagnetic wave detector includes a semiconductor substrate, a first insulating film disposed on the semiconductor substrate and formed so as to expose a part of the semiconductor substrate, a first electrode disposed on the first insulating film, a two-dimensional material layer having a joint part forming a Schottky junction with the semiconductor substrate in a part of the semiconductor substrate, the two-dimensional material layer extending from the joint part to the first electrode over the first insulating film, a second electrode in contact with the semiconductor substrate, and a control electrode disposed at least partly around the joint part in plan view to form a Schottky junction with the semiconductor substrate.