铝掺杂石英粉对多晶硅晶体生长的影响

Effect of Al Doped Quartz Nucleation on the Growth of Multicrystalline Silicon

多晶硅定向凝固铸锭技术生产的硅片是太阳能电池企业主要的原料之一,在多晶硅生长过程中,坩埚底部由于通过气冷降温,所以多晶硅从底部开始结晶。最靠近坩埚底部位置的多晶硅初期形核的质量将决定整个多晶硅晶体的质量。目前很多科研院所和多晶硅片生产企业将多晶硅形核作为研究的重点。从多晶硅形核物质的种类不同可以将形核物质分为以下几种类别:Si、SiO_(2)、Si_(3)N_(4)等,其中SiO_(2)形核由于热膨胀系数与硅相近,而且在诱导多晶硅形核过程中不易熔化,目前是大多数科研院所的研究重点。在SiO_(2)形核物中加入微量的Al粉,将SiO_(2)形核物用喷涂的方式沉积在铸锭坩埚底部,通过传统的铸锭工艺进行多晶硅晶体生长。实验数据表明,SiO_(2)形核物质中添加0.05%的Al粉,初期TC1生长温度设置为1520℃时,可以获得低位错密度的多晶硅晶体。制备成的太阳能电池的效率19%比传统未添加Al粉的SiO_(2)形核物所生产的太阳能电池片高0.3%。

The silicon wafer produced by multicrystalline silicon(Mc-Si)directionally solidified ingot casting technology is one of the main raw materials for solar cell enterprises.During the growth process of Mc-Si,the bottom of the crucible is cooled by air cooling,so the Mc-Si starts to crystallize from the bottom.The quaiity of the initial nucleation of the Mc-Si closest to the bottom of the crucible will determine the mass of the entire Mc-Si crystal.At present,many scientific research institutes and Mc-Si wafer manufacturers focus on Mc-Si nucleation.According to the different types of nucleation materials of Mc-Si silicon,nucleation materials can be divided into the following categories Si,SiO_(2),Si_(3)N_(4),etc.SiO_(2) nucleation is currently the focus of most research institutes because the thermal expansion coefficient of SiO_(2) is similar to silicon and it is not easy to melt in the process of inducing Mc-Si silicon nucleation.Adding trace Al powder to SiO_(2) nucleate and depositing SiO_(2) nucleate at the bottom of the crucible by spraying,the multicrystalline silicon crystal is grown by traditional ingot casting process.Experimental data show that when 0.05%Al powder is added to SiO_(2) nucleate and the initial TC1 growth temperature is set at 1520℃,multicrystalline silicon with low dislocation density can be obtained.The efficiency of the prepared solar cell is 19%,which is 0.3%higher than that of the traditional solar cell produced by SiO_(2) nucleate without Al powder.