CdTe Vapor Deposition Distribution Plate Pressure Gradient
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Solution Overview
Problem
The existing vapor deposition processes for CdTe photovoltaic modules face challenges in achieving uniform thin film deposition, leading to inefficiencies and increased costs due to non-uniformity and material waste, particularly in large-scale production.
Innovation Solution
A vapor deposition apparatus with a distribution plate that creates a pressure gradient by varying the resistance to sublimated source vapors along its longitudinal direction, allowing for a controlled initial and final deposition rate to prevent voids and ensure uniformity of the CdTe layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a constant deposition rate is maintained throughout the substrate, then material utilization is simplified, but voids form during initial deposition and non-uniformity increases
Solution Approach 1:
The patent applies dynamics by transitioning from a static constant deposition rate to a dynamic temporally variable deposition rate. The deposition rate is initially kept low to prevent void formation, then increased to an optimal rate for uniform film formation, and finally maintained at a steady rate. This dynamic adjustment resolves the contradiction between preventing voids and achieving uniform material deposition.
Solution Approach 2:
The patent implements preliminary action by establishing a low deposition rate during the initial stage before the substrate is fully coated. This preliminary low-rate deposition ensures proper nucleation and prevents void formation, creating a foundation for subsequent uniform deposition at higher rates.
2Productivity
If a high deposition rate is used to increase productivity, then production speed increases, but voids are created and film uniformity deteriorates
Solution Approach 1:
The patent applies periodic action by dividing the deposition process into distinct temporal stages: an initial low-rate period for nucleation and void prevention, a transition period for rate increase, and a final steady-state period for uniform high-rate deposition. This periodic structure allows the system to achieve both high productivity and film uniformity by appropriate rate scheduling.
Solution Approach 2:
The deposition rate is made dynamic rather than static, allowing the system to adapt the deposition speed to the current state of film formation. This dynamic control enables high overall productivity while maintaining uniformity by adjusting the rate according to the deposition stage.
3Productivity
If the substrate is positioned close to the CdTe source, then deposition efficiency increases, but vapor pressure uniformity decreases leading to non-uniform deposition
Solution Approach 1:
The patent applies local quality by recognizing that different regions of the substrate experience different vapor pressures due to their positions relative to the CdTe source. The temporally variable deposition rate compensates for these local variations, allowing the system to maintain uniform film quality across the entire substrate while operating at close proximity for high efficiency.
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 results in a more uniform CdTe layer deposition, reducing material waste and increasing the efficiency and cost-effectiveness of large-scale production of CdTe photovoltaic modules.
Implementation Method 1
A heated distribution manifold is disposed below the receptacle and configured to heat said receptacle to a degree sufficient to sublimate source material within the receptacle
Implementation Method 2
The distribution plate defines a pattern of passages therethrough configured to create a pressure gradient in the longitudinal direction from a first longitudinal end to a second longitudinal end
Implementation Method 3
apparatus for vapor deposition of a sublimated source material as a thin film on a photovoltaic module substrate
Data Source
AI summary
Apparatus is generally provided for vapor deposition of a sublimated source material as a thin film on a photovoltaic module substrate. The apparatus includes a distribution plate disposed below the distribution manifold and at a defined distance above a horizontal conveyance plane of an upper surface of a substrate conveyed through the apparatus. The distribution plate defines a pattern of passages therethrough configured to provide greater resistance to the flow of sublimated source vapors at a first longitudinal end than a second longitudinal end. A process for vapor deposition of a sublimated source material to form thin film on a photovoltaic module substrate is also provided via distributing the sublimated source material onto an upper surface of the substrates through a distribution plate positioned between the upper surface of the substrate and the receptacle.