摘要
应用微波光电导衰减仪的方法研究了在不同温度情况下引入铁沾污后再分别进行磷吸杂和等离子体增强化学气相沉积钝化处理对铸造多晶硅片电学性能的影响.实验发现:在中、低温(低于900℃以下)情况下被铁沾污后的多晶硅材料经磷吸杂处理后再结合氢钝化可以显著地改善材料的电学性能;而对于高温(1100℃)情况下被铁沾污后的多晶硅材料经磷吸杂处理后其少子寿命降低,使接着进行的氢钝化也没有明显效果.这表明磷吸杂和氢钝化可以有效地改善被铁沾污后的多晶硅的电学性能,但是改善的效果与铁在硅体内的不同存在形态有关.磷吸杂和氢钝化中只对以间隙态或以其他复合体形态存在的铁有明显的吸杂作用,而对于以沉淀形态存在的铁却没有作用;氢钝化在金属杂质被吸杂移走之后才是最有效的.
The effect of phosphorus gettering or hydrogen passivation on the electrical properties of cast multicrystalline silicon contaminated by iron at different temperatures is investigated by microwave photo conductive decay. It is found that the minority carrier lifetime increases noticeably after phosphorus gettering combined with hydrogen passivation following iron contamination at mid and low temperatures（below 900℃ ）. However, the minority carrier lifetime decreases after phosphorus gettering following iron contamination at high temperature （at 1100℃ ）. These results indicate that phosphorus gettering and hydrogen passivation can effectively improve the electrical performance of cast multicrystalline silicon contaminated by iron, but the effect depends on the different forms of iron existing in the silicon matrix. Phosphorus gettering or hydrogen passivation is useful only for interstitial iron or iron complexes but is of no use for precipitated iron. Also, hydrogen passivation is more effective after most of the iron atoms are removed from the bulk of the silicon matrix.
基金
国家自然科学基金资助项目(批准号:90307010)~~
关键词
铸造多晶硅
铁
磷吸杂
氢钝化
cast multicrvstalline silicon
iron
phosphorus gettering
hydrogen passivation
