Preparation method of casting columnar multi-crystal silicon with large crystal grains in single crystal direction

A polysilicon and large-grain technology, applied in the field of solar photovoltaic power generation, can solve the problems of limited trapping effect and difficulty in improving the photoelectric conversion efficiency of cells, and achieve the effects of improving absorption efficiency, eliminating the reduction of cell efficiency, and reducing grain boundary density

Active Publication Date: 2010-02-24
ZHEJIANG UNIV
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Problems solved by technology

On the other hand, due to the disordered grain orientation of cast polysilicon, the highly efficient anisotropic alkali etching technology cannot be applied to cast polysilicon wafers in the battery manufacturing process to obtain a uniform texture. Therefore, isotropic acid

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] First spread 50 cuboid (length×width×height: 1cm×1cm×1cm) dislocation-free monocrystalline silicon blocks evenly on the bottom of the crucible, and then place 240kg of silicon raw material on these monocrystalline silicon blocks , doped with 20mg of dopant boron, to achieve furnace loading. The furnace chamber was evacuated, and Ar gas was used as a protective gas. Adjust the position of the heat preservation cover, and gradually heat the silicon raw material to above 1410°C, so that the silicon raw material is melted into a liquid, and the upper half of the monocrystalline silicon block at the bottom of the crucible is melted. Finally, cooling water is introduced into the bottom of the crucible for heat exchange, and the heat preservation cover is lifted at a speed of 1mm / min, so that the silicon melt gradually directional solidifies from the bottom upwards, and the unmelted single crystal silicon laid on the bottom acts as a seed crystal to induce grown, cast to for...

Embodiment 2

[0024] Spread 15 cylinders (diameter 5cm, height 2cm) of dislocation-free single crystal silicon blocks evenly on the bottom of the crucible, then place 240kg of silicon raw material on these single crystal silicon blocks, mix 20mg of dopant boron is used for furnace loading. The furnace chamber was evacuated, and Ar gas was used as a protective gas. Adjust the position of the heat preservation cover, and gradually heat the silicon raw material to above 1410°C, so that the silicon raw material is melted into a liquid, and the upper half of the monocrystalline silicon block at the bottom of the crucible is melted. Finally, cooling water is passed into the bottom of the crucible for heat exchange, and the heat preservation cover is lifted at a speed of 2mm / min, so that the silicon melt gradually directional solidifies from the bottom upwards, and the unmelted single crystal silicon laid on the bottom acts as a seed crystal to induce grown, cast to form a boron concentration of...

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Abstract

The invention discloses a preparation method for casting columnar multi-crystal silicon with large crystal grains in the same crystal direction, which comprises the following steps: (1) sequentially putting single-crystal silicon blocks, silicon raw materials and doped elements in a crucible; (2) heating the crucible to melt the silicon raw materials and the doped elements on the single-crystal silicon blocks, wherein all single-crystal silicon block can not be completely melted; and (3) starting heat exchange from the bottom of the crucible, and using the single-crystal silicon blocks as seedcrystals for induced growth and directional solidification to form the multi-crystal silicon. The columnar multi-crystal silicon with large crystal grains can effectively reduce the crystal boundarydensity in the materials and basically solves the problem of the reduction of the battery efficiency caused by the existence of a large number of crystal boundaries in the prior common process of casting the multi-crystal silicon; and meanwhile, the crystal grains in the multi-crystal silicon prepared by the invention have the same crystal direction, so that the high-efficiency alkaline wool making technology in the preparation process of batteries can be used, thereby improving the absorption efficiency of batteries for light.

Description

technical field [0001] The invention belongs to the technical field of solar photovoltaic power generation, and in particular relates to cast polysilicon with single crystal orientation and columnar large crystal grains. Background technique [0002] Solar photovoltaic power generation is currently one of the cleanest, environmentally friendly forms of sustainable energy utilization, and it has developed rapidly around the world in recent years. According to statistics, in the past 10 years, the average annual growth rate of the global photovoltaic industry was 41.3%, and in the past 5 years it was 49.5%. In 2008, it increased by about 60% compared with 2007, and the growth rate increased year by year. Currently commercial solar cells are mainly made of crystalline silicon materials, including single crystal silicon and polycrystalline silicon. Monocrystalline silicon is obtained by the Czochralski method, while polycrystalline silicon is mainly obtained by the casting meth...

Claims

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Application Information

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IPC IPC(8): C30B28/06C30B29/06
Inventor 杨德仁余学功
Owner ZHEJIANG UNIV
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