Laser Processing and Characterization of Diamond and Boron Nitride Films and Related Semiconductor and Superconductor Structures

该基金支持北卡罗莱纳州立大学Jagannadham Kasichainula博士及其同事的研究，该研究涉及金刚石和氮化硼薄膜的激光加工和表征，以及相关的半导体和超导体结构。采用等离子体辅助和热丝辅助化学气相沉积（CVD）方法合成了金刚石薄膜。激光辅助HFCVD在脉冲激光照射下蚀刻去除与金刚石共沉积的石墨相。单腔原位加工技术也得到了发展，通过激光烧蚀可以连续沉积多层。这些方法现在将应用于在SiC和YBa2Cu3O7高tc超导薄膜表面的金刚石沉积，以及在金刚石薄膜上形成激光辅助欧姆接触。这些薄膜将通过超高分辨率和分析透射电子显微镜技术进行表征。为了确定缺陷和界面的原子结构，将采用三步迭代程序，包括原子结构计算，图像模拟以及模拟图像与实验图像的比较。样品将通过拉曼光谱等光学技术进行广泛的表征，并测量微观结构，显微硬度和电导率之间的相关性。该奖项属于材料研究部的电子材料项目。支持的研究方向是金刚石、氮化硼薄膜的合成和表征，以及金刚石和氮化硼在半导体和超导体表面的沉积。这项研究非常重要，因为金刚石及其氮化硼具有独特的机械、电学、光学、热学和化学性质，使其成为耐磨涂层和先进半导体等多种应用的理想材料。对于多晶薄膜而言，当前研究的重点是晶粒尺寸和缺陷等微观结构的控制。在薄膜制造过程中，这些特性的控制对薄膜的性能至关重要。

This grant supports research by Dr. Jagannadham Kasichainula and co-workers at North Carolina State University which deals with laser processing and characterization of diamond and boron nitride films, and related semiconductor and superconductor structures. Diamond thin films have been synthesized using plasma-assisted and hot filament-assisted chemical vapor deposition (CVD) methods. Laser-assisted HFCVD has been used to remove graphitic phase codeposited with diamond by etching with pulsed laser irradiation. Single chamber in situ processing techniques have also been developed with which multiple layers can be deposited sequentially via laser ablation. These methods will now be applied to diamond deposition on such surfaces as SiC and YBa2Cu3O7 high-Tc superconducting thin films, and to formation of laser-assisted ohmic contacts on diamond films. These films will be characterized by ultrahigh resolution and analytical transmission electron microscopy techniques. To determine atomic structure of defects and interfaces, a three-step iterative procedure will be employed, involving atomic structure calculations, image simulation, and comparison between simulated and experimental images. Samples will be extensively characterized by optical techniques such as Raman spectroscopy, and correlations between microstructure, microhardness, and electrical conductivity will be measured. %%% This award is in the Electronic Materials Program of the Division of Materials Research. The research supported is directed at synthesis and characterization of thin films of diamond, boron nitride, and depositions of diamond and boron nitride on semi- and superconductor surfaces. This research is of importance because the unique mechanical, electrical, optical, thermal, and chemical properties of diamond and its boron nitride relative make them ideal materials for applications as diverse as wear-resistant coatings and advanced semiconductors. For polycrystalline films, key current research issues are those of microstructure control in such areas as grain size and defects. Control of these properties in thin film fabrication is critical to performance.