Shallow Junction Silicon Solar Cell Emitter With Low-Resistance Contact
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Solution Overview
Problem
Conventional solar cell manufacturing processes struggle to achieve a shallow junction diffusion emitter with low sheet resistance and high surface concentration, leading to alloy ohmic contact issues and reduced photoelectric conversion efficiency.
Innovation Solution
A preparation method combining a diffusion process with low-temperature diffusion and high-temperature drive-in, and a chain oxidation process, to achieve a shallow junction diffusion emitter with a junction depth of about 0.15 μm, improving surface doping concentration and ohmic alloy contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional diffusion process is used to prepare shallow junction with depth of 0.1 μm-0.2 μm, then junction depth is reduced, but sheet resistance becomes extremely high and surface concentration becomes low, leading to alloy ohmic contact problems
Solution Approach 1:
The diffusion process is divided into three distinct stages with different temperature profiles: a first low-temperature stage for initial doping, a second low-temperature stage for refined doping control, and a high-temperature drive-in stage for uniform distribution. This segmentation allows independent optimization of each stage to achieve both shallow junction depth and controlled sheet resistance.
Solution Approach 2:
The patent employs dynamic temperature parameter changes throughout the diffusion process, transitioning from low temperature (700-800°C) in initial stages to high temperature (900-1000°C) in the drive-in stage, then back to low temperature for final refinement. These parameter changes enable precise control over doping concentration and distribution to resolve the contradiction between shallow depth and acceptable sheet resistance.
2Length of moving object
If diffusion process is optimized to achieve shallow junction, then junction depth is reduced, but photoelectric conversion efficiency decreases due to low surface concentration
Solution Approach 1:
The first low-temperature diffusion stage performs preliminary doping action to establish the initial doping profile and surface concentration before the subsequent stages. This preliminary action ensures adequate surface concentration is built up early, which is then maintained and refined in later stages, preventing photoelectric conversion efficiency loss.
Solution Approach 2:
The patent maintains continuous doping action throughout all three stages, with each stage contributing to the final doping profile. The continuous process ensures that surface concentration is progressively built and maintained at optimal levels, preventing the efficiency loss that would occur with discontinuous or single-stage processes.
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 method significantly enhances the photoelectric conversion efficiency of solar cells by improving shortwave absorption and achieving better ohmic contacts, resulting in a 0.1% relative efficiency increase compared to conventional solar cells.
Implementation Method 1
a diffusion process with low-temperature diffusion and high-temperature drive-in
Implementation Method 2
a chain oxidation process with high-temperature chain oxidation
Data Source
AI summary
The present application provides a preparation method and application of a crystalline silicon solar cell having a shallow junction diffusion emitter. The preparation method comprises a diffusion process and a chain oxidation process, the diffusion process comprises low temperature diffusion and high temperature propulsion, and the chain oxidation process comprises high-temperature chain oxidation. According to the present application, firstly, a low-doped diffusion shallow junction having a depth of 0.15 um is prepared by means of optimization of the diffusion process, and doping with a certain dose concentration is formed on the surface of a diffusion layer by using photon thermal activation radiation energy of high-temperature chain oxidation, so as to solve the mismatch problem of alloy ohmic contact subsequently formed with silver paste, and finally, the photoelectric conversion efficiency is improved to a high degree.