Effect of High-Temperature Annealing on Ion-Implanted Silicon Solar Cells

P-type and n-type wafers were implanted with phosphorus and boron, respectively, for emitter formation and were annealed subsequently at 950∼1050∘C for 30∼90 min for activation. Boron emitters were activated at 1000∘C or higher, while phosphorus emitters were activated at 950∘C. QSSPC measurements show that the implied Voc of boron emitters increases about 15 mV and the J01 decreases by deep junction annealing even after the activation due to the reduced recombination in the emitter. However, for phosphorus emitters the implied Voc decreases from 622 mV to 560 mV and the J01 increases with deep junction annealing. This is due to the abrupt decrease in the bulk lifetime of the p-type wafer itself from 178 μs to 14 μs. PC1D simulation based on these results shows that, for p-type implanted solar cells, increasing the annealing temperature and time abruptly decreases the efficiency (Δηabs=−1.3%), while, for n-type implanted solar cells, deep junction annealing increases the efficiency and Voc, especially (Δηabs=+0.4%) for backside emitter solar cells

Design and measurements of high-performance metasurface diffractive waveguide systems

In recent years, Augmented Reality (AR) glasses have emerged as groundbreaking wearable devices, enabling a harmonious integration of virtual information with the real world. However, challenges remain in enhancing the optical systems that underpin AR glasses, including resolution and field of view limitations. This research focuses on leveraging metasurfaces, composed of subwavelength nanostructures, to design and optimize advanced optical components for AR glasses. By tailoring the properties of metasurfaces, such as amplitude, phase, and polarization control, we aim to overcome limitations and enhance the resolution, field of view, and overall visual performance of AR glasses. To achieve truly immersive AR experiences, improving the optical performance is essential. This involves minimizing aberrations, enhancing contrast, reducing glare, and optimizing light transmission efficiency. Metasurfaces offer unique capabilities for precise manipulation of light at the nanoscale, enabling the creation of highly efficient and compact optical components. By integrating metasurface-based elements, such as gratings, lenses, beam splitters, and polarization controllers, we can enhance resolution, expand the field of view, and improve overall optical performance. Furthermore, metasurfaces offer multifunctionality and the potential for dynamic control. By combining multiple functionalities within a single metasurface-based element, the complexity of optical systems can be reduced, leading to more compact and lightweight AR glasses. Additionally, incorporating tunable or switchable elements within metasurfaces enables real-time control of optical properties, allowing for adaptation to changing environmental conditions and advanced functionalities like adaptive focus and depth perception. This research also explores the challenges of small eyebox in Maxwellian view systems, which restricts user head movement and comfort. Innovative methods utilizing input angle modulation at the metasurface optical element (MOE) are proposed to increase the eyebox size while maintaining optical performance. The study includes the design and optimization of metasurface gratings, algorithm development for optimizing optical elements, implementation of a high-resolution full-color prototype, and investigation of imaging techniques like ultrafast light field tomography (LIFT). By combining these research efforts, this study aims to significantly advance the design and optimization of metasurface-based diffractive waveguide systems for AR applications. The outcomes have the potential to revolutionize the field of augmented reality, pushing the boundaries of optical resolution, addressing limitations, and enhancing the overall user experience. The findings contribute to the advancement of AR glasses, enabling new possibilities in industries such as education, entertainment, healthcare, and beyond.

Metasurface wavefront control for high-performance user-natural augmented reality waveguide glasses.

Augmented reality (AR) devices, as smart glasses, enable users to see both the real world and virtual images simultaneously, contributing to an immersive experience in interactions and visualization. Recently, to reduce the size and weight of smart glasses, waveguides incorporating holographic optical elements in the form of advanced grating structures have been utilized to provide light-weight solutions instead of bulky helmet-type headsets. However current waveguide displays often have limited display resolution, efficiency and field-of-view, with complex multi-step fabrication processes of lower yield. In addition, current AR displays often have vergence-accommodation conflict in the augmented and virtual images, resulting in focusing-visual fatigue and eye strain. Here we report metasurface optical elements designed and experimentally implemented as a platform solution to overcome these limitations. Through careful dispersion control in the excited propagation and diffraction modes, we design and implement our high-resolution full-color prototype, via the combination of analytical-numerical simulations, nanofabrication and device measurements. With the metasurface control of the light propagation, our prototype device achieves a 1080-pixel resolution, a field-of-view more than 40°, an overall input-output efficiency more than 1%, and addresses the vergence-accommodation conflict through our focal-free implementation. Furthermore, our AR waveguide is achieved in a single metasurface-waveguide layer, aiding the scalability and process yield control

Effect of High-Temperature Annealing on Ion-Implanted Silicon Solar Cells

P-type and n-type wafers were implanted with phosphorus and boron, respectively, for emitter formation and were annealed subsequently at 950∼1050 • C for 30∼90 min for activation. Boron emitters were activated at 1000 • C or higher, while phosphorus emitters were activated at 950 • C. QSSPC measurements show that the implied V oc of boron emitters increases about 15 mV and the J 01 decreases by deep junction annealing even after the activation due to the reduced recombination in the emitter. However, for phosphorus emitters the implied V oc decreases from 622 mV to 560 mV and the J 01 increases with deep junction annealing. This is due to the abrupt decrease in the bulk lifetime of the p-type wafer itself from 178 μs to 14 μs. PC1D simulation based on these results shows that, for p-type implanted solar cells, increasing the annealing temperature and time abruptly decreases the efficiency (Δη abs = −1.3%), while, for n-type implanted solar cells, deep junction annealing increases the efficiency and V oc , especially (Δη abs = +0.4%) for backside emitter solar cells