Collaborative Research: Developing metal-organic molecular beam epitaxy (MOMBE) for chalcogenide semiconductor thin film synthesis

非技术概述有许多已知的半导体材料，它们的不同特性使不同的技术成为可能，从照相机到太阳能电池，到计算机，到高速电信等等。最近已经显示出一类称为硫属钙钛矿的新型半导体具有独特的特性组合，使得这些材料有希望用于太阳能电池应用。 迄今为止，制造这些材料需要高温和缓慢的晶体生长速度。未来的技术开发和商业上可行的制造将需要一种方法来使这些材料更快，更低的温度。马萨诸塞州理工学院和塔夫茨大学的研究人员之间的这一合作项目得到了NSF材料研究部门的固态和材料化学与陶瓷计划的支持，将开发一种新的化学方法，使硫属钙钛矿比迄今为止更快，更低的温度，而不会牺牲材料质量。 这一基础科学的见解也将为其他半导体家族的研究和开发提供信息，并对计算技术产生潜在影响。 该项目通过培养半导体化学和材料研究的研究生来培养未来的劳动力。 该项目还通过支持实习计划--指导学术产业网络（GAIN）--为社区大学学生提供劳动力培训机会，该计划为波士顿地区社区大学的学生提供学术界和工业界材料研究和开发的经验。技术摘要马萨诸塞州理工学院和塔夫茨大学的研究人员之间的这一合作项目，在NSF材料研究部门的固态和材料化学与陶瓷计划的支持下，专注于硫属化物薄膜生长的基础研究，开发通过金属有机分子束外延（MOMBE）制造高质量硫属化物化合物半导体外延薄膜的工艺。 含有难熔金属（例如Zr）的硫属化物化合物半导体目前受到广泛关注。 在中等温度下的高质量薄膜加工对于推动基础研究和实现未来的制造（包括异质集成）是必要的，但是仍然存在来自极低蒸气压金属与极高蒸气压硫属元素的组合的重大科学障碍。这项工作的三个高层次目标是：（1）研究使用金属有机（MO）前体合成锆基硫属化物化合物半导体;（2）开发分子束外延（MBE）的变体，允许新的硫属化物化合物半导体晶体薄膜;（3）扩大社区大学生的劳动力培训机会。 该项目的合作方法始于通过塔夫茨的蒸发测量和金属有机化学气相沉积（MOCVD）筛选来评估和向下选择MO前体。 麻省理工学院的MOMBE实验可以集中在外延薄膜生长的高值参数空间内。 化学分析和薄膜表征能力的组合，可在整个合作允许在固-气界面的成膜反应的详细研究。 除了为研究生提供培训机会外，该项目还通过指导性学术行业网络（GAIN）为社区大学生扩大劳动力培训机会。 在该项目中，当地社区大学的学生通过两次暑期实习（一次在学术界，另一次在工业界）获得材料研究和开发方面的经验。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-Technical SummaryThere are many known semiconducting materials, and their different properties are what enable different technologies, from cameras, to solar cells, to computers, to high-speed telecommunications, and so on. A new class of semiconductors called chalcogenide perovskites has been recently shown to feature a unique combination of properties that make these materials promising for solar cell applications. To-date, making these materials has required high temperatures and slow rates of crystal growth. Future technology development and commercially viable manufacturing will require a method to make these materials faster and at lower temperatures. This collaborative project between researchers at the Massachusetts Institute of Technology and Tufts University, supported by the Solid State and Materials Chemistry and Ceramic Programs in NSF’s Division of Materials Research, will develop a new chemical approach for making chalcogenide perovskites faster and at lower temperatures than hitherto possible, without sacrificing material quality. Insights from this fundamental science will also inform research and development of other families of semiconductors, with potential impact in computing technologies. This project develops the future workforce by training graduate students in semiconductor chemistry and materials research. This project also expands workforce training opportunities for community college students by supporting an internship program – the Guided Academic Industry Network (GAIN) – that provides students from Boston-area community colleges experiences in materials research and development in academia and industry.Technical SummaryThis collaborative project between researchers at the Massachusetts Institute of Technology and Tufts University, supported by the Solid State and Materials Chemistry and Ceramic Programs in NSF’s Division of Materials Research, focuses on fundamental studies of chalcogenide thin film growth, developing processes to make high-quality, epitaxial thin films of chalcogenide compound semiconductors by metal-organic molecular beam epitaxy (MOMBE). Chalcogenide compound semiconductors containing refractory metals (such as Zr) are of widespread current interest. High-quality thin film processing at moderate temperatures is necessary to propel basic research, and to enable future manufacturing (including heterogeneous integration), but there remain significant scientific hurdles stemming from the combination of very-low vapor pressure metals with very-high vapor pressure chalcogens. Three high-level objectives of this work are: (1) studying the synthesis of Zr-based chalcogenide compound semiconductors using metal-organic (MO) precursors; (2) developing a variation on molecular beam epitaxy (MBE) that allows new access to crystalline films of chalcogenide compound semiconductors; and (3) expanding workforce training opportunities for community college students. The collaborative approach of this project begins with evaluation and down-selection of MO precursors through evaporation measurements and metal-organic chemical vapor deposition (MOCVD) screening at Tufts. MOMBE experiments at MIT can then focus within a high-value parameter space for epitaxial thin film growth. The combination of chemical analysis and film characterization capabilities available across the collaboration allows detailed study of the film-forming reactions at the solid-vapor interface. In addition to providing training opportunities for graduate students, this project expands workforce training opportunities for community college students through the Guided Academic Industry Network (GAIN). In this program, students at local community colleges acquire experience in materials research and development through two summer internships, one in academia and a second one in industry.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.