Graphene as a Diffusion Barrier in High-Temperature Electronics*

The development of high-temperature semiconductor technology for use in applications such as power plants, nuclear reactors, and on hot planets like Venus (~460°C) is severely limited by the failure of essential metal contacts in otherwise thermally robust devices. This failure, which manifests as bubbling on the metal contact, is thought to be due to inter-diffusion of metal and semiconductor layers. To test this hypothesis, we constructed a monolayer graphene barrier to see if bubble formation would be reduced. Auger electron spectroscopy was used to characterize the inter-diffusion of material layers in Pd/AlGaN/GaN and Pd/Graphene/AlGaN/GaN Schottky diodes subjected to thermal treatments over a range of temperatures from 100 to 450°C. Graphene was shown to stop bubble formation in high-temperature metal contacts up to 425°C, supporting the inter-diffusion hypothesis and demonstrating promise for use on, for example, the planet Mercury (where temperatures range from approximately -180 to 430°C).