Spin-dependent transport in fully processed silicon solar cells studied by pulsed Multifrequency Electrically Detected Magnetic Resonance below 600 MHz/20 mT and at 263 GHz/9.4 T

目的是研究自旋相关的输运机制，以通过连续波和脉冲电检测磁实验（pEDMR）在从< 600 MHz/20 mT到263 GHz/200 MHz/200 mT的极端频率/场范围内确定具有最先进效率的完全加工的薄膜和基于晶片的硅太阳能电池中的决定顺磁状态的功能。9.4使用BeJEL现有和新开发的全套EPR光谱仪，特别是位于HZB的263 GHz和X-和Q-波段光谱仪。（分别为a-Si：H和poly-Si），在不同硅相之间的边界处的顺磁缺陷（例如非晶硅/晶体硅界面和多晶硅的晶界）以及在通过无序（a-Si：H）引起的局域态处的顺磁缺陷影响太阳能转换效率。由于现有技术硅太阳能电池的总体缺陷浓度较低，界面/边界区域在纳米范围内，因此需要EDMR等超灵敏间接EPR检测方案来提高微波检测技术的灵敏度极限。在本研究中，EDMR将是特别有用的，由于它的能力，连接设备限制电荷传输和传输限制顺磁状态的结构信息的损失机制。我们将进一步改进263 GHz cw和pEDMR实验，特别是专注于实现更高的B1场强，以在100 ns范围内实现pi/2倍。此外，我们还将进一步开发专用薄膜EPR和EDMR探头以及互补的甚低频（10-600 MHz）EDMR和ENDOR激励方案。最近采用的pEDMR检测方案将被修改为分别在263 GHz和600 MHz的操作，用于分配尚未解决的顺磁状态和自旋相关的传输路径方式。这些实验将在HZB制造的不同小型化最先进的太阳能电池架构上进行。工作包是：1.具有适当同位素富集（28 Si，29 Si，2D）的a-Si/c-Si和薄膜Si太阳能电池的生长。开发一种新的EDMR触点设计，可增强B1场。2.优化了263 GHz EPR/EDMR探头的设计，以提高微波功率.在相同的设置中在263 GHz和10-600 MHz处实现pEDMR方法。c-Si和薄膜Si太阳电池的多频连续波和pEDMR实验.在单个芯片上实现完整的连续波V波段EPR和EDMR检测设置。结合导电AFM和EPR实验研究a-Si/c-Si界面.用DFT方法模拟了不同硅相界面及其亚界面区的EPR参量，并考虑了激子态和输运。

The objective is to study spin dependent transport mechanisms to identify function determining paramagnetic states in fully processed thin film and wafer-based silicon solar cells with state of the art efficiencies by cw and pulsed electrically detected magnetic experiments (pEDMR) in an extreme frequency/field regime from < 600 MHz/20 mT up to 263 GHz/ 9.4 using the full set of EPR spectrometers available and newly developed at BeJEL with particular emphasis on the 263 GHz and X- and Q-band spectrometer located at HZB.In wafer-based c-Si, as well as amorphous and polycrystalline silicon thin film Si solar cells (a-Si:H and poly-Si, respectively), paramagnetic defects at the boundary between different silicon phases such as amorphous/crystalline silicon interfaces and grain boundaries of polycrystalline silicon as well as at localized states induced through disorder (a-Si:H) influence the solar conversion efficiency. Due to the low overall defect concentration in state of the art silicon solar cells, with interface/boundary regions in the nm range, ultra-sensitive indirect EPR detection schemes like EDMR are required to lift the sensitivity limit of microwave detected techniques. In the present study EDMR will be particularly useful due to its capability to connect device limiting charge transport and loss mechanisms with structural information on transport limiting paramagnetic states. We will further improve the 263 GHz cw and pEDMR experiment, particularly focusing on achieving higher B1 field strength to achieve pi/2 times in the 100 ns regime. In addition we will further develop dedicated thin-film EPR and EDMR probe heads and a complementary very low frequency (10-600 MHz) EDMR and ENDOR excitation scheme. Recently employed pEDMR detection schemes will be modified for operation at 263 GHz and 600 MHz respectively for the assignment of yet unresolved paramagnetic states and spin dependent transport path ways. These experiments will be conducted on different miniaturized state-of the art solar cell architectures manufactured at HZB. The work packages are:1. Growth of a-Si/c-Si and thin film Si solar cells with appropriate isotope enrichment (28Si, 29Si, 2D). Development of a new EDMR contact design that will result in a strong B1 field enhancement.2. Optimizing the design of the 263 GHz EPR/EDMR probe head for enhanced microwave power.3. Implementation of pEDMR methods at 263 GHz and 10-600 MHz in the same setup.4. Multi frequency cw and pEDMR experiments on c-Si and thin-film Si solar cells.5. Implementation of a complete cw V-band EPR and EDMR detection setup on a single chip.6. Combined conductive AFM and EPR experiments on a-Si/c-Si interfaces.7. Modeling of EPR parameters of the interface between different silicon phases and their sub-interface region by DFT methods taking excitonic states and transport into account.