Crystallographic- and oxynitride-based surface
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Photoelectrochemical water splitting devices face challenges due to the instability of efficient photo-absorbers, which degrade quickly due to chemical and photochemical corrosion, and durable materials exhibit poor efficiency, leading to issues like loss of photocurrent and poor charge transfer.
Innovation Solution
A method involving the formation of a stabilizing layer with a uniform distribution of oxynitride material on the surface of semiconductor compositions, such as gallium nitride, to enhance durability and efficiency by incorporating oxygen through oxidation reactions or electrochemical procedures, creating a continuous or discontinuous oxynitride layer that acts as both a passivation and activation layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If efficient photo-absorbers like Si and III-V semiconductors are used, then photo-absorption efficiency is improved, but stability deteriorates due to chemical and photochemical corrosion
Solution Approach 1:
An oxynitride layer is introduced as an intermediary between the semiconductor photo-absorber and the electrolyte. This intermediate layer provides both chemical stability to prevent corrosion and appropriate band alignment to maintain efficient charge carrier transfer, thus resolving the contradiction between stability and photo-absorption efficiency
Solution Approach 2:
The patent uses composite material structures combining semiconductor photo-absorbers with oxynitride protection layers. The composite structure leverages the high photo-absorption efficiency of semiconductors while the oxynitride component provides chemical stability and corrosion resistance, achieving both improved efficiency and stability simultaneously
2Reliability
If durable materials like TiO2 and SrTiO3 are used, then stability is improved, but photo-absorption efficiency deteriorates
Solution Approach 1:
The device is segmented into distinct functional layers: a dedicated photo-absorber layer for efficient light harvesting and an oxynitride protection layer for stability. This segmentation allows each layer to be optimized for its specific function without compromising the other, resolving the contradiction between durability and efficiency
3Reliability
If thick metal oxide passivation layers are used, then stability is improved, but charge transfer deteriorates due to poor electron transport
Solution Approach 1:
The patent optimizes the thickness parameter of the oxynitride layer to a specific range that balances protection and charge transfer. The layer is thin enough to allow efficient electron transport but thick enough to provide adequate corrosion protection, resolving the contradiction between stability and charge transfer efficiency
4Reliability
If protection layers are added to prevent corrosion, then stability is improved, but photocurrent loss increases due to undesired light absorption
Solution Approach 1:
The oxynitride layer provides localized protection exactly where needed at the semiconductor-electrolyte interface, rather than using thick bulk protection layers. This localized approach minimizes light absorption losses while providing sufficient corrosion resistance, resolving the contradiction between stability and photocurrent maintenance
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 oxynitride layer improves the stability and performance of photoelectrochemical devices by reducing corrosion, maintaining photocurrent density, and enhancing charge transfer, allowing for sustained hydrogen production with high Faradaic efficiency without the need for electrocatalysts.
Implementation Method 1
incorporating oxygen into the surface to form a stabilizing layer on the surface
Implementation Method 2
the electrocatalyst, which sometimes also acts as a protection layer, lowers the overpotential, mediates the charge carrier transfer, and provides active sites for the chemical reaction at solid/liquid interface
Implementation Method 3
GaN is suitable as an efficient protective layer for silicon photocathodes, due to the almost ideal band alignment of the two materials for providing optimal electron transport
Implementation Method 4
creating a continuous or discontinuous oxynitride layer that acts as both a passivation and activation layer
Data Source
AI summary
A method of fabricating a device includes providing a substrate of the device, forming a structure of the device, the structure being supported by the substrate, having a semiconductor composition, and including a surface, where nitrogen is present at the surface, and incorporating oxygen into the surface to form a stabilizing layer on the surface. Incorporating oxygen into the surface is implemented such that the stabilizing layer includes a uniform distribution of an oxynitride material