Schottky Photodiode Structure for Broadband Visible-NIR Sensing
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Solution Overview
Problem
Conventional silicon-based photodiodes have limited quantum efficiency in the near-infrared band due to poor light absorption, and materials like Ge or InGaAs are difficult to grow and integrate with silicon substrates, making them expensive and limited in application.
Innovation Solution
A photodiode with a Schottky junction structure layer and a pinning layer on a semiconductor substrate, using a conductive material and semiconductor layer combination that allows for efficient absorption of light across a broad band, including visible and infrared ranges, through internal photoemission and photovoltaic mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silicon-based P-N junction photodiode is used, then high quantum efficiency in the visible light band is achieved, but light absorption in the near-infrared band is poor
Solution Approach 1:
The patent employs a composite structure combining silicon substrate with a Schottky junction layer formed by metal or transparent conductive oxide materials. This composite approach allows the photodiode to maintain silicon's excellent visible light response while the Schottky junction enables near-infrared detection through internal photoemission, achieving broadband spectral coverage from visible to near-infrared regions.
Solution Approach 2:
The invention changes the detection mechanism parameter by utilizing internal photoemission at the Schottky junction interface rather than relying solely on silicon's bandgap absorption. By adjusting the Schottky barrier height through material selection and doping, the photodiode can detect photons with energies below silicon's bandgap, extending sensitivity into the near-infrared band while preserving visible light performance.
2Adaptability or versatility
If materials like Ge or InGaAs are used to improve near-infrared absorption, then light absorption in the near-infrared band is enhanced, but the materials are difficult to grow or synthesize on silicon substrates
Solution Approach 1:
The patent introduces a Schottky junction layer as an intermediary between the silicon substrate and the incident light. This intermediate layer with appropriate work function creates a potential barrier that enables internal photoemission, allowing near-infrared detection without requiring direct growth of Ge or InGaAs on silicon. The Schottky junction acts as a mediator that bridges the gap between silicon's optical limitations and near-infrared detection requirements.
Solution Approach 2:
The invention replaces the mechanical/chemical process of growing complex semiconductor materials (Ge or InGaAs) on silicon substrates with a simpler physical process of forming a Schottky junction. Instead of relying on complex epitaxial growth or molecular beam epitaxy to create lattice-matched heterostructures, the patent uses standard semiconductor fabrication techniques to deposit metal or TCO layers that form Schottky barriers, significantly simplifying the manufacturing process.
3Adaptability or versatility
If a Schottky junction structure with conductive material and pinning layer is implemented, then broadband light absorption from visible to infrared is achieved, but the device complexity increases
Solution Approach 1:
The photodiode structure is segmented into distinct functional layers: the silicon substrate for visible light detection, the Schottky junction layer for near-infrared detection through internal photoemission, and the pinning layer for potential control. This segmentation allows each layer to be optimized for its specific function while using standard semiconductor fabrication processes, managing complexity through functional decomposition rather than attempting to create a monolithic broadband detector.
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 solution enables high responsivity and quantum efficiency across a wide wavelength band from 400 nm to 1700 nm, effectively sensing both visible and infrared light, and simplifies the manufacturing process, reducing production costs compared to traditional P-N junction technologies.
Implementation Method 1
The photodiode achieves high responsivity and quantum efficiency across a wide wavelength range, including both visible and infrared bands, by utilizing internal photoemission and photovoltaic mechanisms
Implementation Method 2
The photodiode achieves high responsivity and quantum efficiency across a wide wavelength range, including both visible and infrared bands, by utilizing internal photoemission and photovoltaic mechanisms
Implementation Method 3
a pinning layer disposed adjacent to the Schottky junction structure layer, the pinning layer and fixing potentials of the semiconductor substrate and the first layer
Data Source
AI summary
A photodiode according to an embodiment includes a semiconductor substrate, a Schottky junction structure layer disposed on the semiconductor substrate and including a first layer including a conductive material and a semiconductor layer, and a pinning layer disposed adjacent to the Schottky junction structure layer and fixing potentials of the semiconductor substrate and the first layer.