Graphene has extraordinary mechanical and electronic properties, making it a promising material for membrane based nanoelectromechanical systems (NEMS). Here, chemical-vapor-deposited graphene is transferred onto target substrates to suspend it over cavities and trenches for pressure-sensor applications. The development of such devices requires suitable metrology methods, i.e., large-scale characterization techniques, to confirm and analyze successful graphene transfer with intact suspended graphene membranes. We propose fast and noninvasive Raman spectroscopy mapping to distinguish between freestanding and substrate-supported graphene, utilizing the different strain and doping levels. The technique is expanded to combine two-dimensional area scans with cross-sectional Raman spectroscopy, resulting in three-dimensional Raman tomography of membrane-based graphene NEMS. The potential of Raman tomography for in-line monitoring is further demonstrated with a methodology for automated data analysis to spatially resolve the material composition in micrometer-scale integrated devices, including free-standing and substrate-supported graphene. Raman tomography may be applied to devices composed of other two-dimensional materials as well as silicon micro- and nanoelectromechanical systems.
Freestanding and permeable nanoporous gold membranes for surface-enhanced Raman scattering
表面增强拉曼光谱（SERS）需要可靠的高增强基底，以便用于不同的应用领域。在这里，我们介绍了独立的多孔金膜（PAuM）作为易于生产，可扩展，机械稳定，有效的SERS基板。我们制造大规模的子30厚PAuM，形成独立的膜，根据标称的金厚度不同的形态。这些PAuM是机械稳定的压力高达$>3$酒吧，并表现出表面增强拉曼散射与局部增强因子的$10^4$到$10^5$，我们证明了波长依赖性和空间分辨拉曼测量使用石墨烯作为本地拉曼探针。数值模拟表明，增强来自个别的，纳米级的膜孔作为光学缝隙天线。我们的PAuM是机械稳定的，提供了强大的SERS增强的激发功率密度高达$10^6$ W $\,$ cm $^{-2}$，并可能会发现使用作为一个积木在流通传感器应用的基础上SERS。
Thermal analysis of GaN-based photonic membranes for optoelectronics
Universität Bremen（不来梅大学）；MAPEX Center for Materials and Processes, Universität Bremen（不来梅大学材料过程MAPEX中心）；Chalmers University of Technology（查尔姆斯理工大学）；Humboldt-Universität zu Berlin（柏林洪堡大学）；MIT-IBM Watson AI Lab, IBM Research（麻省理工学院-IBM沃森人工智能实验室，IBM研究部）；École Polytechnique Fédérale de Lausanne (EPFL)（洛桑联邦理工学院）
Nano-engineered surface enhanced Raman spectroscopy substrates for probing tissue-material interactions
MIT（麻省理工学院）；University of Wyoming（怀俄明大学）；Brigham and Women's Hospital（布莱根和妇女医院）；Harvard Medical School（哈佛医学院）；Ragon Institute of MGH, MIT and Harvard（MGH、麻省理工学院和哈佛拉贡研究所）；Jameel Clinic for AI & Healthcare, MIT（麻省理工学院贾米尔人工智能与医疗诊所）
