报告题目：Growth of high quality Si ingots for solar cells using the dendritic cast method and the noncontact crucible method
报告时间：11月25日（周五）上午10点
报告地点：硅材料国家重点实验室一号楼会议室
邀请人：杨德仁教授
ABSTRACT
The most important subject of the cast method will be the assurance of the high yield of higher efficiency solar cells than 19.0 % for the regular cell structure. We proposed the noncontact crucible (NOC) method to obtain uniform large Si single ingots with sufficient quality to obtain solar cells with a high conversion efficiency and a high yield using a cast furnace. In this method, the Si melt has a large low-temperature region in its upper central part to allow natural crystal growth inside it. Nucleation occurs on the surface of the Si melt using a seed crystal, and an ingot grows inside the Si melt without contact with the crucible wall. A furnace with two zone heaters was developed to design as a simpler furnace for practical use. A single ingot with a maximum diameter ratio of 0.9 and a maximum diameter of 45.0 cm was obtained using a 50 cm diameter crucible. The etch pit density in the centre of these ingots was generally on the order of 102 ‒ 104cm-2 without necking technique.Minority carrier lifetime at the injection level of 1 × 1015/cm3 was 1- 3 ms after P gettering.A p-type ingot was grown after furnace cleaning. The solar cells were prepared using full wafers (15.6 × 15.6 cm2) cut from the ingot by the FREA AIST standard process. Using the same solar cell structure and process to obtain an average conversion efficiency of 19.1% for p-type Czochralski (CZ) wafers, the highest conversion efficiency of 19.14% and the average conversion efficiency of 19.0% were obtained for our wafers. The scattering width was only 0.34% which was quite narrow because of its high uniformity. Using the cast furnace, p-type solar cells with the conversion efficiency and yield as high as those of CZ solar cells were obtained by the NOC method for the first time.
