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

目的是研究自旋依赖传输机制来识别函数确定顺州完全加工薄膜和wafer-based与最先进的硅太阳能电池效率的连续波和脉冲电检测磁实验(pEDMR)在一个极端的频率/字段政权从< 600 MHz / 20吨到263 GHz / 9.4使用全套的电子顺磁共振光谱仪和新开发的非性病性梅毒特别强调263 GHz和X - q波段光谱仪位于HZB。在基于晶片的c-Si、非晶和多晶硅薄膜硅太阳电池（分别为a-Si:H和poly-Si）中，不同硅相（如非晶/晶硅界面和多晶硅晶界）边界处的顺磁缺陷以及无序诱导的局域态（a-Si:H）都会影响太阳能转换效率。由于目前硅太阳能电池整体缺陷浓度较低，界面/边界区域在nm范围内，因此需要EDMR等超灵敏的间接EPR检测方案来提高微波检测技术的灵敏度限制。在本研究中，EDMR将特别有用，因为它能够将器件限制电荷输运和损耗机制与输运限制顺磁性态的结构信息联系起来。我们将进一步改进263 GHz连续波和pEDMR实验，特别注重实现更高的B1场强，在100 ns范围内达到pi/2倍。此外，我们将进一步开发专用薄膜EPR和EDMR探头以及互补的极低频（10-600 MHz） EDMR和ENDOR激励方案。最近采用的pEDMR检测方案将分别修改为263 GHz和600 MHz的工作，以分配尚未确定的顺磁态和自旋相关的传输路径。这些实验将在HZB制造的不同的微型化最先进的太阳能电池结构上进行。工作包是：1。生长具有适当同位素富集（28Si, 29Si, 2D）的a-Si/c-Si和薄膜Si太阳能电池。开发一种新的EDMR触点设计，将导致强大的B1场增强。263 GHz EPR/EDMR探头优化设计，增强微波功率。在263 GHz和10-600 MHz的相同设置下实现pEDMR方法。c-Si和薄膜硅太阳能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。a-Si/c-Si界面导电AFM和EPR联合实验。考虑激子态和输运的DFT方法对不同硅相界面及其子界面区域的EPR参数进行建模。

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.