CdTe Photovoltaic Device Back Contact Interface Cleaning
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Solution Overview
Problem
Existing methods for preparing photovoltaic devices fail to effectively remove surface contaminants from semiconductor layers, leading to poor interfaces between the semiconductor and back contact layers, which negatively affects the device's performance, particularly in terms of VOC and ROC.
Innovation Solution
A method involving the deposition of a semiconductor absorber layer, followed by cleaning using dry etching or wet etching processes to remove contaminants, and subsequent removal of surface moisture before depositing a back contact layer, specifically using ZnTe for improved crystallographic matching and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If surface contaminants are removed using known methods, then the interface quality between semiconductor layer and back contact layer is improved, but the grain boundary and lattice of the semiconductor layer are negatively affected
Solution Approach 1:
The patent employs dry etching and wet etching processes with specific chemical compositions and process parameters to selectively remove surface contaminants while preserving the underlying crystal structure. By controlling etch time, temperature, and chemical concentration, the method achieves effective contamination removal without damaging the semiconductor layer's grain boundaries and lattice.
Solution Approach 2:
The patent performs surface cleaning operations (dry etching and wet etching) as preliminary steps before depositing the back contact layer. This preliminary action removes oxidation, hydrocarbons, and other contaminants from the semiconductor layer surface, creating an optimal interface foundation that prevents subsequent adhesion and electrical contact problems.
2Stability of the object's composition
If surface contaminants are not removed, then the semiconductor layer structure is preserved, but the interface between semiconductor layer and back contact layer deteriorates
Solution Approach 1:
The patent uses controlled dry etching and wet etching processes that selectively target surface contaminants while leaving the bulk semiconductor structure intact. By adjusting process parameters such as etch duration, chemical composition, and temperature, the method achieves differential removal: aggressive enough to eliminate oxidation and hydrocarbons, yet gentle enough to preserve the crystal lattice.
Solution Approach 2:
The patent introduces intermediate cleaning steps (dry etching followed by wet etching) between semiconductor layer formation and back contact layer deposition. These intermediate processes act as mediators that eliminate surface contaminants without directly contacting or damaging the underlying semiconductor structure, thereby protecting the lattice while improving interface quality.
3Manufacturing precision
If aggressive cleaning methods are used to remove contaminants, then surface cleanliness is improved, but surface moisture and potential damage increase
Solution Approach 1:
The patent performs preliminary cleaning operations (dry etching and wet etching) to remove organic and inorganic contaminants before the semiconductor layer is fully assembled. This preliminary action prevents subsequent contamination issues without requiring aggressive post-assembly cleaning that could introduce moisture or damage sensitive interfaces.
Solution Approach 2:
The patent uses dry etching and wet etching solutions as intermediary cleaning agents that effectively remove contaminants without leaving residual moisture. The controlled chemical processes ensure thorough cleaning while the subsequent rapid processing and protective measures prevent moisture re-adsorption, thereby avoiding the harmful effects of surface moisture.
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 enhances the interface quality between the semiconductor and back contact layers, resulting in increased efficiencies of photovoltaic devices, with efficiencies exceeding 17% and 14.3% for PV cells and devices, respectively, by minimizing contamination and altering surface stoichiometry for better electrical contact.
Implementation Method 1
cleaning the semiconductor absorber layer to remove contaminants therefrom using a dry etch and/or a wet etch
Implementation Method 2
cleaning the semiconductor absorber layer to remove contaminants therefrom using a dry etch and/or a wet etch
Implementation Method 3
depositing a semiconductor absorber layer adjacent to a substrate
Implementation Method 4
depositing a semiconductor absorber layer adjacent to a substrate
Data Source
AI summary
A method to improve CdTe-based photovoltaic device efficiency is disclosed, the method including steps for removing surface contaminants from a semiconductor absorber layer prior to the deposition or formation of a back contact layer on the semiconductor absorber layer, the surface contaminants removed using at least one of a dry etching process and a wet etching process.