The US Navy shows an interest in graphene in a recently published patent application, aiming to protect a method for growth of high-quality thin films on graphene. The most common use of such thin films on graphene is in high-speed electronics.
US Patent Application number 20130017323 describes a method for the preparation of graphene surfaces for subsequent atomic layer deposition of dielectric films. The dielectrics in question are primarily aluminum oxide and hafnium oxide, commonly used as spacer layers between the graphene and a gate in electronic transistors. The document shows images which confirm that the preparation method results in films of much higher quality than those grown on unprepared surfaces. Electrical tests confirm that, in contrast with a reduced quality of key electrical properties typically associated with atomic layer deposition on graphene, with the new method electrical properties stay intact. The invention is scalable for mass production of graphene transistors for high speed electronics.
The main downside of the method is the environmental unfriendliness of the chemicals used for preparation of the graphene surface. The chemical treatment involves the use of Xenon, which could be toxic in some forms, and Fluorine gas, which is highly toxic and a hazard to the environment. Other suggested methods include hydrofluoric acid and a solution that swallows all things organic, aptly named “piranha”. The use of toxic substances is in sharp contrast to the global trend of using “green processes” in graphene production. The scale of production and immediate applications remain, naturally, unclear. The assignee of the application is “the Government of the United States of America, as represented by the Secretary of the Navy”. The addresses of the inventors point to the Center for Naval Analyses (CNA), a federally funded research and development center.
IBM has put a lot of effort into improving the quality of thin dielectrics on graphene. It remains to be seen whether the company will start using the Navy’s patent, or keep refining their own methods.