Generation of a Pristine Sapphire Surface by Oxidation and Solid State Conversion of a Sputtered Al Coating

通过溅射铝涂层的氧化和固态转化生成原始蓝宝石表面

• 批准号: 0211078
• 负责人: Helen Chan
• 金额: $ 60万
• 依托单位: Lehigh University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-10-01 至 2007-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0211078&HistoricalAwards=false
• 关键词: Generation; Pristine; Sapphire; Surface; Oxidation

This project consists of an in-depth investigation into the mechanisms behind a novel method for generating a pristine sapphire surface. The process is named AGOG, representing the three processing steps: Al thin film deposition on sapphire, Growth of an aluminum Oxide layer, and grain Growth to produce a single crystal surface. Processing conditions at each step in the AGOG process will be varied systematically and correlated to the resulting changes in surface structure. The effect of Al film microstructure and thickness on oxidation behavior will be determined. Sapphire of (0001), (11-20), and (01-12) orientation will be used to identify the effect of interface conditions on the Al to alumina phase transformation. Studies of phase transition behavior will be carried out concurrently with oxidation/heating rate experiments. Once a polycrystalline alumina layer has been created, solid-state conversion processing conditions will be examined. Finally, strategies for eliminating hillock growth during the initial oxidation step will be explored.Sapphire, the single crystal form of alumina, is utilized in many important commercial applications where the quality of the final surface finish is critical. One example is the recent use as a substrate material for high-power blue light emitting diodes (LED's) and laser diodes. These devices are required for a large number of applications including full color electroluminescent displays, and read-write laser sources for high-density information storage on magnetic and optical media. The successful commercial production of blue LED's also offers the potential for bright, white light sources derived from solid state devices. Advantages over conventional incandescent and fluorescent sources include far higher energy efficiency and increased reliability. Sapphire is also widely used for visible and midwave infrared (IR) airborne windows and radomes for guidance systems. Currently, the surfaces of sapphire components are finished by a combination of mechanical and chemical polishing. The final polishing steps are time-consuming, and typically make up a significant fraction of the total cost. The AGOG process is a potentially more cost-effective method for achieving a high quality surface finish in sapphire.

该项目包括对生成原始蓝宝石表面的新方法背后的机制进行深入研究。 该工艺被命名为 AGOG，代表三个加工步骤：蓝宝石上的铝薄膜沉积、氧化铝层的生长以及晶粒生长以产生单晶表面。 AGOG 工艺中每个步骤的加工条件都会系统地变化，并与表面结构的最终变化相关。将确定铝膜微观结构和厚度对氧化行为的影响。 (0001)、(11-20) 和 (01-12) 取向的蓝宝石将用于确定界面条件对 Al 到氧化铝相变的影响。相变行为的研究将与氧化/加热速率实验同时进行。一旦形成多晶氧化铝层，将检查固态转化加工条件。最后，将探讨在初始氧化步骤中消除小丘生长的策略。蓝宝石（氧化铝的单晶形式）用于许多重要的商业应用，其中最终表面光洁度的质量至关重要。 一个例子是最近用作高功率蓝色发光二极管 (LED) 和激光二极管的基板材料。 这些设备是大量应用所必需的，包括全色电致发光显示器以及用于磁和光介质上高密度信息存储的读写激光源。 蓝色 LED 的成功商业化生产还为源自固态器件的明亮白光光源提供了潜力。 与传统白炽灯和荧光光源相比，其优点包括更高的能源效率和更高的可靠性。蓝宝石还广泛用于制导系统的可见光和中波红外 (IR) 机载窗口和天线罩。 目前，蓝宝石部件的表面是通过机械抛光和化学抛光相结合的方式完成的。 最终的抛光步骤非常耗时，并且通常占总成本的很大一部分。 AGOG 工艺是一种潜在更具成本效益的方法，可实现蓝宝石的高质量表面光洁度。