2D Material Electromagnetic Detector With Unipolar Dark-Current Barrier
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electromagnetic wave detectors face challenges in reducing dark current while maintaining photocarrier extraction efficiency, primarily due to the sensitivity of two-dimensional material states to surrounding charges and the formation of barriers that impede carrier extraction.
Innovation Solution
The introduction of a unipolar barrier layer between the semiconductor layer and the two-dimensional material layer, which is electrically connected to both, allows for the suppression of dark current without impeding photocarrier extraction by acting as an electron or hole barrier depending on the conductivity types of the semiconductor and two-dimensional material layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a Schottky barrier is formed between doped graphene and doped silicon substrate to reduce dark current, then dark current is reduced, but electrons thermally excited in graphene may be emitted through the Schottky barrier due to sensitive changes in the density of states of two-dimensional material caused by surrounding charges
Solution Approach 1:
An insulating film is introduced as an intermediary layer between the graphene layer and the silicon substrate. This insulating film prevents direct contact while allowing electrical connection, thereby stabilizing the Schottky barrier height by isolating the graphene from charge fluctuations in the substrate and surrounding environment, while still enabling the barrier to function in suppressing dark current
Solution Approach 2:
The electrical connection between graphene and silicon substrate is achieved by controlling the insulating film's properties (thickness, material composition) to allow tunneling or weak conduction. This parameter adjustment enables the system to maintain stable Schottky barrier characteristics while preventing thermionic emission of electrons
2Productivity
If a pn junction is formed in the semiconductor layer with two-dimensional material layer to function as photodiode, then photocurrent amplification is achieved, but barriers at the junction interface impede extraction of photocarriers
Solution Approach 1:
The insulating film serves as a mediator that enables the pn junction to function as a photodiode for photocurrent amplification while preventing the formation of harmful interface barriers. By positioning the insulating film strategically, it allows optical field penetration for carrier generation while maintaining smooth carrier extraction paths
Solution Approach 2:
The device structure is segmented into distinct functional regions: the pn junction region for photocurrent generation and amplification, and the insulating film region for barrier prevention and electrical connection. This segmentation allows each region to optimize its function without interfering with the other
3Productivity
If negative voltage applied to pn junction is increased to enhance hole extraction efficiency, then hole extraction is improved, but electrons thermally excited in two-dimensional material layer flow into semiconductor layer to increase dark current
Solution Approach 1:
The insulating film acts as a voltage-dropping intermediary that allows the application of negative voltage to enhance hole extraction efficiency while preventing the voltage from causing excessive electron injection from the two-dimensional material layer into the semiconductor layer, thereby suppressing dark current increase
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 while ensuring efficient extraction of photocarriers, allowing for increased operating temperatures and larger voltage applications without compromising photocurrent production.
Implementation Method 1
a Schottky barrier is formed at the interface between graphene sufficiently doped with an n-type or p-type impurity and a silicon substrate doped with a p-type or n-type impurity to produce a current rectifying effect
Implementation Method 2
electrons thermally excited in graphene may be emitted (thermionic emission) and injected into the silicon substrate across the Schottky barrier
Implementation Method 3
when the pn junction interface is irradiated with an electromagnetic wave, a gate voltage is applied in a pseudo manner to the graphene through the insulating film to modulate the conductivity of the two-dimensional material layer. Consequently, photocurrent is amplified
Data Source
AI summary
An electromagnetic wave detector includes a semiconductor layer, an insulating layer disposed on the semiconductor layer and having an opening, a two-dimensional material layer extending from on the opening to on the insulating layer, including a connection part in contact with a peripheral part of the insulating layer facing the opening, and electrically connected to the semiconductor layer, a first electrode part disposed on the insulating layer and electrically connected to the two-dimensional material layer, a second electrode part electrically connected to the semiconductor layer, and a unipolar barrier layer disposed between the semiconductor layer and the connection part of the two-dimensional material layer and electrically connected to each of the semiconductor layer and the two-dimensional material layer.