Photoelectric Conversion Device Using Surface Plasmons
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Solution Overview
Problem
Conventional photoelectric conversion devices using semiconductor band gaps face limitations in resolution due to light diffraction, and require specific incident angles and two electrodes to excite surface plasmons, making them inefficient for image sensors.
Innovation Solution
A photoelectric conversion device with a metal light receiving portion featuring a slot-shaped slit on its front surface, allowing perpendicular incident light to excite surface plasmons without the need for prisms or rear electrodes, and utilizing a voltage detection portion to measure electric potential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional semiconductor photoelectric conversion devices are used, then the device structure is simple, but the resolution is limited by light diffraction
Solution Approach 1:
The patent changes the fundamental photoelectric conversion mechanism from semiconductor band gap absorption to surface plasmon excitation. This parameter change enables resolution beyond the diffraction limit while maintaining a relatively simple device structure consisting of a metal film with a slit and electrode patterns.
Solution Approach 2:
The patent employs a composite structure combining metal materials (for plasmon excitation) with semiconductor materials (for charge generation and collection). This composite approach allows the device to overcome diffraction limitations while maintaining structural simplicity and manufacturing feasibility.
2Manufacturing precision
If surface plasmons are excited using conventional methods, then resolution beyond diffraction limit is achieved, but prisms are required and incident light must be at predetermined angles
Solution Approach 1:
The patent extracts and eliminates the prism component from the surface plasmon excitation system. By using a metal film with a slit structure directly on the sensor surface, the device achieves plasmon excitation with perpendicular incident light, removing the need for external prisms and angle adjustment mechanisms.
Solution Approach 2:
The metal film with slit structure serves multiple functions: it acts as both the plasmon excitation element and the optical interface for perpendicular incident light. This multi-functional design simplifies the overall device structure by integrating what were previously separate components (prism and sensor surface) into a single element.
3Device complexity
If surface plasmons are excited with perpendicular incident light, then device structure is simplified, but conventional two-electrode configuration is still required
Solution Approach 1:
The patent merges the electrode patterns with the optical structure. The electrode patterns are integrated into the same layer or plane as the slit structure, allowing for simplified fabrication and reduced device complexity while maintaining the two-electrode configuration necessary for charge collection.
4Ease of operation
If metal light receiving portion with slit is used, then perpendicular incident light can excite surface plasmons, but manufacturing precision of slit is critical
Solution Approach 1:
The patent uses a slit structure in a metal film, which can be fabricated using standard semiconductor fabrication techniques such as lithography and etching. The slit acts as a sub-wavelength aperture that enables plasmon excitation while being compatible with existing manufacturing processes, balancing manufacturing precision requirements with operational simplicity.
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
Enables efficient detection of incident light without diffraction limits, simplifying the device structure and eliminating the need for angle adjustments, while allowing for the conversion of perpendicular light into surface plasmons for improved image sensor performance.
Implementation Method 1
the incident light is caused to excite surface plasmons through the slit
Implementation Method 2
photoelectric conversion devices adapted to convert surface plasmons, which induce no diffraction limits, into electric currents
Implementation Method 3
an electric potential at the front surface of the light receiving portion caused by the surface plasmons is measured by the voltage detection portion
Data Source
AI summary
There is provided a photoelectric conversion device utilizing surface plasmons, including: a plate-shaped light receiving portion which made of metal, provided on a most superficial surface of the photoelectric conversion device, and having a front surface and a rear surface so as to receive incident light at the front surface; a slot-shaped slit provided in the front surface of the light receiving portion; and a voltage detection portion adapted to measure an electric potential at the front surface of the light receiving portion; wherein the incident light is caused to excite surface plasmons through the slit, and an electric potential at the front surface of the light receiving portion induced by the surface plasmons is measured by the voltage detection portion.