Plasmonic Photodetector Nanohole Structure for Small-Pixel Quantum Efficiency
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Solution Overview
Problem
Conventional photodetectors face limitations in reducing detector size and pixel size due to direct light absorption into smaller gates, leading to inefficient photoelectric conversion and low internal quantum efficiency.
Innovation Solution
The proposed photodetector utilizes surface plasmon polaritons (SPPs) generated at metal-dielectric interfaces to enhance light sensing capabilities. By shielding incident light with a metal layer and creating nanoholes with a higher dielectric constant, SPPs are absorbed by a light absorbing layer, exciting charges that tunnel through an insulation film, thereby inducing photocurrent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If incident light is directly absorbed into a smaller gate, then the detector size and pixel size can be reduced, but light excitation does not occur and photoelectric conversion efficiency decreases
Solution Approach 1:
The patent introduces surface plasmon polaritons (SPPs) as an intermediary mechanism to bridge incident light and the semiconductor gate. The metal layer acts as a mediator that converts optical energy into SPPs, which then generate strong localized electric fields that can effectively excite charges in the semiconductor gate, enabling photoelectric conversion in sub-wavelength structures.
Solution Approach 2:
The patent changes the physical state and parameters of light-matter interaction by utilizing surface plasmon resonance. By adjusting the metal layer properties, dielectric constant, and SPP excitation conditions, the system achieves enhanced electric field confinement and improved photoelectric conversion efficiency in reduced-size detectors.
2Volume of moving object
If the gate size is reduced to decrease detector size, then miniaturization is achieved, but internal quantum efficiency of photoelectric conversion decreases
Solution Approach 1:
The patent transitions from direct optical absorption in the gate to a two-stage process: first generating SPPs at the metal-dielectric interface, then utilizing the evanescent field of SPPs to excite charges. This dimensional transition from direct light-gate interaction to indirect SPP-mediated interaction enables efficient photoelectric conversion in sub-wavelength structures.
Solution Approach 2:
The patent modifies the interaction parameters by introducing surface plasmon resonance conditions, adjusting metal layer thickness, dielectric constant, and SPP excitation wavelength to maximize field enhancement and charge generation efficiency in miniaturized detectors.
3Measurement precision
If a metal layer is introduced to generate SPPs, then light sensing capability is enhanced, but device structure becomes more complex
Solution Approach 1:
The metal layer serves multiple functions: it acts as an SPP generation interface, provides field enhancement, and can function as part of the electrode structure. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving enhanced light sensing capability.
Solution Approach 2:
The patent combines the metal layer with the gate structure, merging the SPP generation function with the existing photodetector architecture. This integration approach minimizes additional structural complexity while achieving enhanced light sensing through SPP-mediated photoelectric conversion.
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 approach maximizes light sensing capability and internal quantum efficiency by leveraging the enhanced electric field effects of SPPs, allowing for efficient photoelectric conversion and improved photocurrent generation.
Implementation Method 1
utilizing the phenomenon that collective oscillations of free electrons, known as surface plasmons (SPs) are created by coupling between light and free electrons on a metal surface and combined with light waves into surface plasmon polaritons (SPPs), and the SPPs create a strongly enhanced electric field at a metal-dielectric interface
Implementation Method 2
a light absorbing layer absorbing the generated SPPs and allowing charges excited by the absorbed SPPs and a localized electric field effect to tunnel through an insulation film
Implementation Method 3
charges which have absorbed energy tunnel into the gate from a channel region formed between the oxide film and the silicon substrate or a drain electrode to which a driving voltage is applied, through the oxide film
Implementation Method 4
The photodetector is typically formed to bring about photoelectric conversion by absorbing light into the gate
Data Source
AI summary
A photodetector includes a metal layer that shields incident light and generates surface plasmon polaritons (SPPs), a light absorbing layer that absorbs the generated SPPs and allows charges excited by the absorbed SPPs and a localized electric field effect to tunnel, a dielectric formed at nanoholes in which at least a part of the metal layer is opened, and a semiconductor layer that induces the photocurrent based on an electric field effect of tunneled electrons. The SPPs form localized surface plasmons (LSPs) at an interface where the metal layer meets the dielectric.