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

其目的是研究自旋相关的输运机制，以确定决定全工艺薄膜和晶片基硅太阳电池顺磁状态的函数，并通过连续波和脉冲电检测磁实验(PEDMR)在极端频率/场条件下从&lt；600 MHz/20mT至263 GHz/9.4使用BeJEL最新开发的全套EPR光谱仪，特别是位于HZB的263 GHz和X-Q波段光谱仪。在晶片基c-Si，以及非晶硅和多晶硅薄膜硅太阳电池(分别为a-Si：H和多晶硅)中，不同硅相之间的顺磁缺陷，如非晶/晶硅界面和多晶硅的晶界，以及由无序(a-Si：H)诱导的局域态，都会影响太阳能转换效率。由于目前技术水平的硅太阳能电池的总缺陷浓度较低，界面/边界区域在纳米范围内，因此需要像EDMR这样的超灵敏间接EPR检测方案来提高微波检测技术的灵敏度极限。在目前的研究中，EDMR将特别有用，因为它能够将器件限制电荷传输和损失机制与限制顺磁状态的传输的结构信息联系起来。我们将进一步改进263 GHz CW和pEDMR实验，特别是在100 ns范围内实现更高的B1场强，达到pi/2倍。此外，我们还将进一步开发专用的薄膜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探测方案将被修改为分别在263 GHz和600 MHz下工作，以分配尚未分辨的顺磁态和自旋相关的输运路径。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。工作包包括：1.a-Si/c-Si和具有适当同位素丰度(28Si、29Si、2D)的薄膜硅太阳电池的生长。开发一种新的EDMR触点设计，将导致强大的B1场增强。优化了263 GHz EPR/EDMR探头的设计，提高了微波功率。在相同的设置下实现了263 GHz和10-600 MHz的pEDMR方法。对单晶硅和薄膜硅太阳电池进行了多频CW和pEDMR实验。在单个芯片上实现完整的CW V波段EPR和EDMR检测设置。A-Si/c-Si界面的电导AFM和EPR联合实验。考虑激子态和输运的DFT方法模拟了不同硅相及其亚界面区界面的EPR参数。

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.