Surface Passivation for High Efficiency Crystalline Silicon Solar Cells

为了研究高效晶体硅太阳电池的钝化效果，在单晶硅和多晶硅衬底上分别沉积了单层或双层氮化硅（SiNx：H）薄膜和非晶硅（a-Si：H）薄膜。有效载流子寿命和热退火效应进行了评估。得到以下结果. SiNx：H薄膜的钝化效果：富Si薄膜比富N薄膜的有效寿命有更大的提高.热退火对有效寿命的影响：SiNx：H薄膜的有效寿命随退火温度和退火时间的变化而变化。FTIR分析结果表明，H原子的迁移改变了Si-H键和N-H键的密度，这与钝化效果有关. SiNx的钝化效果：H/ SiNx：H双层：通过SiNx的组合：不同折射率的H薄膜，有效寿命都有较大的提高。还可以控制表面反射特性。4. SiNx：H/ a-Si：H双层膜的钝化效应：在250 ℃低温下沉积了SiNx：H/ a-Si：H双层膜。发现这些层对于有效载流子寿命显示出极高的改善效果。此外，热退火还提高了有效寿命. a-Si：H单层的钝化效果：在250 ℃下沉积的a-Si：H单层中，通过400-500 ℃的热退火，有效寿命得到极大的改善。太阳能电池钝化膜的评估：太阳能电池实际上是在我们的实验室制造的。评价了电池表面SiNx：H膜和电池背场表面a-Si：H膜的影响。其结果，确认了转换效率的改善效果。

To investigate the passivation effects for high efficiency crystalline silicon solar cells, single layers or double layers of silicon nitride (SiNx : H) film and amorphous silicon (a-Si : H) film were deposited on mono-crystalline and multi-crystalline silicon substrates. The effective carrier lifetime and the thermal annealing effect were evaluated. The following results were obtained.1. Passivation effects of SiNx : H films : Si rich films showed larger improvement of effective lifetime than N rich films.2. Thermal annealing effect for the effective lifetime : The effective lifetimes in SiNx : H films were largely changed by temperature and duration of thermal annealing. From the results of FTIR, it was confirmed that the densities of Si-H and N-H bonds are changed by H atoms migration and this behavior is related to the passivation effect.3. Passivation effects of SiNx : H/ SiNx : H double layers : By combination of SiNx : H films with different refractive indices, the effective lifetimes were more improved. Also it is possible to control the surface reflective property.4. Passivation effects of SiNx : H/ a-Si : H double layers: SiNx : H/ a-Si : H double layers were deposited at low temperature of 250C. These layers were found to show extremely high improvement effect for the effective carrier lifetimes. Moreover the effective lifetimes were increased by thermal annealing.5. Passivation effects of a-Si:H single layers: In a-Si:H single layers deposited at 250 C, the effective lifetimes were extremely improved by thermal annealing at 400-500 C.6. Evaluation of passivation films for solar cells : The solar cells were actually made in our laboratory. The effects of SiNx : H film on the surface of the cell and a-Si : H film on the BSF layer of the cell were evaluated. As a result, improvement effects for conversion efficiency were verified.