Optical switching based on transition metal oxide thin films

拟议的NSERC-CRD拨款是与思科系统公司合作的，其总体目标是合成，表征和展示热稳定的金属氧化物薄膜，并同时应用于光和电开关。只有表现出电和热刺激的金属-绝缘体（MI）跃迁（MITs）的材料将被认为是潜在的最有趣的。在这些材料中，二氧化钒（VO2）是研究最多且技术成熟的材料之一。它显示了一个突然的MIT，可能是电（由电场）和热（由温度变化）引起的。然而，这种MI转变的温度只有50 - 70℃，这使得这种材料容易受到温度波动的影响，容易发生不必要的开关。该CRD的目标是合成一系列具有更高转变温度的电和热刺激MIT的材料。结构必须稳定，装置必须可靠。本项目将进行以下研究：(a)磁控溅射法合成各种氧化钒薄膜。(b)寻找和发现各种氧化钒相。(c)制备条件、薄膜成分、结构和性能之间的关系。(d)通过改变钒氧化程度来修改MIT。(e)用其他过渡金属部分取代钒来修饰VO2。(f)评估(a)至(e)中用于MIT光开关的薄膜的热稳定性和可用性。拟议的CRD拨款建立在申请人在薄膜和光学特性领域的专业知识基础上。CRD将在麻省理工学院（MIT）基于过渡金属（钒）氧化物的光开关领域产生新的先进知识。研究结果有望为新一代光电开关的开发打开大门，并对光通信和微电子技术产生直接影响。

The proposed NSERC-CRD grant is in collaboration with Cisco Systems, and has the overall goal of synthesizing, characterizing and demonstrating thermally stable metal-oxide thin films with applications in simultaneous optical and electrical switching. Only materials exhibiting electrically and thermally stimulated metal-insulator (MI) transitions (MITs) will be considered as potentially the most interesting. Among these materials, vanadium dioxide (VO2) is one of the most studied and having the established technology. It shows an abrupt MIT which may be induced electrically (by an electric field) and thermally (by temperature change). However, the temperature of this MI transition is only 50 - 70 C, which makes this material vulnerable to temperature fluctuations and prone to unwanted switching. The goal of this CRD is to synthesize a range of materials having electrically and thermally stimulated MIT with higher transition temperatures. The structure has to be stable and the device has to be reliable. During the course of this project the following research will be undertaken: (a) The synthesis of various vanadium oxide thin films by magnetron sputtering. (b) Search and discovery of various vanadium oxide phases. (c) The relationship between fabrication conditions, film composition, structure and properties. (d) The modification of MIT by varying the level of vanadium oxidation. (e) VO2 modification by partial substitution of vanadium by other transition metals. (f) Assessment of thermal stability and usability of thin films in (a) to (e) for MIT for optical switching. The proposed CRD grant builds on the expertise the applicants have in the area of thin films and optical properties. The CRD will generate new advanced knowledge in the area of MIT for optical switching based on transition metal (vanadium) oxides. The results are expected to open the door to the development of a new generation of optical and electrical switches and to have a direct impact in optical communications and microelectronics.