Chalcopyrite Solar Cell Precursor Stack Fabrication
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Solution Overview
Problem
Existing methods for producing chalcopyrite compound semiconductors, such as Cu(In,Ga)Se2 and Cu(In,Ga)S2, face challenges in achieving optimal crystal quality and efficiency in thin-film solar cells due to limitations in precursor layer formation and heat treatment processes.
Innovation Solution
A three-stage method involving the deposition of precursor layers with specific chalcogen compositions and heat treatment in a chalcogen-containing atmosphere, allowing for a definable gallium and sulfur depth profile, which influences the band gap and crystal quality of the semiconductor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a two-step process with precursor layers is used for producing chalcopyrite compound semiconductors, then the crystal formation and phase transformation can be achieved through heat treatment, but the manufacturing complexity and process time are increased compared to one-stage co-evaporation
Solution Approach 1:
The production process is divided into distinct stages: first depositing metal precursor layers (Cu, In, Ga), then depositing chalcogen layers (S, Se), and finally performing heat treatment to form the chalcopyrite compound. This segmentation allows each layer to be optimized independently for crystal quality while maintaining process control.
Solution Approach 2:
Metal precursor layers are deposited and prepared in advance before chalcogen deposition and heat treatment. This preliminary preparation of the metal layer structure enables better control over the subsequent crystal formation process and improves overall manufacturing precision.
2Manufacturing precision
If multiple precursor layers with specific compositions are deposited before heat treatment, then the gallium and sulfur depth profile can be optimized for band gap control, but the deposition process time and manufacturing steps are increased
Solution Approach 1:
Different depth profiles of gallium and sulfur are created within the layer structure to achieve specific band gap characteristics. The metal precursor layers and chalcogen layers are deposited with varying compositions to create the desired local chemical environment for optimal optoelectronic properties.
Solution Approach 2:
The composition control extends into the depth dimension of the material structure. By controlling the vertical distribution of elements through multi-layer deposition, the patent achieves precise band gap engineering that cannot be obtained through uniform composition alone.
3Reliability
If heat treatment is performed in a chalcogen-containing atmosphere to convert precursor layers to compound semiconductor, then the crystal quality and phase purity are improved, but the energy consumption and process complexity are increased
Solution Approach 1:
Heat treatment is performed in a controlled atmosphere containing chalcogen elements, which provides a protective environment that prevents unwanted oxidation and ensures complete conversion of precursor layers to the desired chalcopyrite phase. This controlled atmosphere improves phase purity while managing energy requirements.
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 method enhances the open-circuit voltage and efficiency of thin-film solar cells by optimizing the gallium and sulfur content distribution, leading to improved crystal quality and increased energy conversion efficiency.
Implementation Method 1
In a first stage, the first precursor layer is produced by depositing the metals copper (Cu), indium (In) and gallium (Ga) onto a body. In a second stage, the second precursor layer is produced by depositing at least one chalcogen, selected from sulfur (S) and selenium (Se), on the first precursor layer.
Implementation Method 2
The resulting layer structure with the precursor layers is heat treated in a second process. The heat treatment causes the actual crystal formation and phase transformation of the precursor layers to form the actual semiconductor layer.
Implementation Method 3
A further step for heat treating the at least one precursor layer stack in a process space during a first time interval such that the metals of the first precursor layer, the at least one chalcogen of the second precursor layer and the metals of the third precursor layer form the pentanary compound semiconductor Cu (In,Ga)(S,Se) 2 can be reactively converted into the quaternary compound semiconductor Cu(In,Ga)Se 2 or into the quaternary compound semiconductor Cu(In,Ga)S 2.
Data Source
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AI summary
The present invention relates to a method for producing a compound semiconductor (2), comprising the following steps: - Producing at least one precursor layer stack (11), consisting of a first precursor layer (5.1), a second precursor layer (6) and a third precursor layer (5.2), wherein said first precursor layer (5.1) is formed in a first stage by precipitating the metals copper, indium and gallium onto a body (12), and said second precursor layer (6) is produced in a second stage by precipitating at least one chalcogen, selected from sulphur and selenium, onto said first precursor layer (5.1), and said third precursor layer (5.2) is produced in a third stage by precipitating the metals copper, indium and gallium onto said second precursor layer (6); - Pre-treating the at least one precursor layer stack (11) in a process chamber (13) such that the metals of said first precursor layer (5.1), the at least one chalcogen of said second precursor layer (6) and the metals of the third precursor layer (5.2) are reactively converted to form said compound semiconductor (2).