Chemical vapor deposition of hexagonal boron nitride and its use in electronic devices

Abstract

Dielectrics are insulating materials used in many different electronic devices and play an important role in all of them. Current advanced electronic devices use dielectric materials with a high dielectric constant and avoid high leakage currents. However, these materials show several intrinsic problems, and also a bad interaction with adjacent materials. Therefore, the race for finding a suitable dielectric material for current and future electronic devices is still open. In this context two dimensional [2D] materials have become a serious option, not only thanks to their advanced properties, but also to the development of scalable synthesis methods. Graphene has been the most explored 2D material for electronic devices. However, graphene has no band gap, and therefore it cannot be used as dielectric. MoS2 and other 2D transition metal dichalcogenides (TMDs) are semiconducting 2D materials that can provide more versatility in electronic devices. In this PhD thesis I have investigated the use of monolayer and multilayer hexagonal boron nitride (h-BN) as dielectric for electronic devices, as it is a 2D material with a band gap of ~5.9 eV. My work has mainly focused on the synthesis of the h-BN using chemical vapor deposition, the study of its intrinsic morphological and electrical properties at the nanoscale, and its performance as dielectric in different electronic devices, such as capacitors and memristors. Overall, our experiments indicate that h-BN is a very reliable dielectric material, and that it can be successfully used in capacitors and memristors. Moreover, h-BN shows additional performances never observed in traditional dielectrics, such as volatile resistive switching, which may also open the door for new applications.