Исследование спектральных свойств когерентного дифракционного излучения от периодических структур

При пролете электрона вблизи периодической структуры генерируется поляризационное излучение, называемое дифракционным излучением от периодических структур (grating diffraction radiation). При пролете электрона параллельно решетке возникает хорошо изученное излучение Смита-Парселла. Однако при непараллельном пролёте также может возникать излучение. В данной работе проводится анализ спектральных характеристик когерентного дифракционного излучения от решеток, экспериментально полученных на ускорителе KEK-LUCX (г. Цукуба, Япония). Представлены спектры излучения, получаемые при разных углах ориентации решетки. Полученные спектральные характеристики сравниваются с теоретически рассчитанными.When an electron passes close to the periodic structure polarization radiation is generated, called diffraction radiation from periodic structures (grating diffraction radiation). When an electron passes parallel to the grating, well-studied Smith-Purcell radiation arises. However, in the case of a nonparallel flight, radiation can also occur. In this work, we analyze the spectral characteristics of coherent diffraction radiation from gratings, experimentally obtained at the accelerator KEK-LUCX (Tsukuba, Japan). Radiation spectrums obtained at different angles of grating orientation are presented. The obtained spectral characteristics are compared with theoretically calculated

The irresistible charm of a simple current flow pattern - approaching 25% with a solar cell featuring a full-area back contact

Screen-printed Al-BSF silicon solar cells have dominated the PV market for decades. Their long-term success is based on a low-complexity cell architecture and a robust production sequence. The full-area rear contact allows a simple and effective one-dimensional current flow pattern in the base resulting in high fill factors. Some of the successor technologies of this simple but yet successful cell architecture, i.e. PERL and IBC solar cells, have a significantly higher process and pattern complexity. This presentation discusses a cell structure with an architecture very similar to the classical Al-BSF solar cell but with a higher efficiency potential. This is achieved by substituting the full-area doped back surface region by a passivated contact scheme consisting of a tunnel oxide covered by a heavily doped silicon film, called TOPCon. The current champion efficiency of 24.9% (Voc = 719 mV) on n-type silicon shows that this structure has a high potential while keeping the process effort low and the current flow pattern simple. The very high fill factor of 83.4% results from both, the very low recombination and transport losses caused by this contact scheme. This presentation will give a detailed overview on the ongoing improvement and up-scaling of the TOPCon technology

Potential gain in multicrystalline silicon solar cell efficiency by n-Type doping

This study aims for a quantitative investigation of the material limitations and the efficiency potential of an entire multicrystalline (mc) n-type silicon block in comparison with an mc p-type block of the same purity level in order to predict the potential of mc n-type silicon for the industrial production of solar cells. Therefore, two standard mc silicon blocks were crystallized under identical conditions (same high purity feedstock, crucible system, and temperature profiles), only differing in their type of doping. The material quality of wafers along the whole block height is analyzed after different solar cell process steps by photoluminescence imaging of the diffusion length. The bulk recombination related efficiency losses are assessed by an “efficiency limiting bulk recombination analysis (ELBA),” combining injection dependent lifetime images with PC1D cell simulations. The influence of the base resistivity variation along the block is considered in the PC1D cell simulations and backed up by Sentaurus Device simulations. This analysis predicts a significantly higher material-related efficiency potential after typical solar cell processes along the whole block height for mc n-type silicon compared with mc p-type silicon. In addition, the efficiency potential for mc n-type silicon depends less on block position