Atomic layer deposition (ALD) is the more suitable technique to grow materials as ultra-thin layers. The peculiar self-limited and layer-by-layer mechanism is the reason for the growth of very uniform and conformal films, with nanometric thickness control, using relatively low deposition temperatures. Due to the described potential characteristics, it is considered the growth method of choice for several microelectronics fields, where the progressive scaling-down of devices involves deposition methods with nanometric-level accuracy. In this context, the application of ALD is mainly focused on the deposition of high-κ dielectrics. The high-κ materials are very promising as gate insulators for the next generation of high-power/frequency transistors based on wide bandgap (WBGs) semiconductors (SiC, GaN). Contextually, their integration with 2D materials (Graphene, MoS2) has been demonstrated to be highly beneficial for their intrinsic properties and devices performance.
In this presentation, ALD growth of high-κ dielectrics on WBGs and 2D-materials, will be discussed and particular attention will be paid to the outstanding issues and the strategies for the improvement of their properties and their integration in electronic devices.
[1] E. Schilirò, P. Fiorenza, G. Greco, M. Monforte, G. G. Condorelli, F. Roccaforte, F. Giannazzo, R. Lo Nigro, “Early growth stage of aluminum oxide (Al2O3)insulating layer by thermal- and plasma enhanced atomic layer deposition on AlGaN/GaN heterostructures” ACS Appl. Electron. Mater., 4, 1, 406–415 (2022).
[2] E. Schilirò, R. Lo Nigro, S. E. Panasci, S. Agnello, M. Cannas, F. M. Gelardi, F. Roccaforte, F. Giannazzo, “Direct Atomic Layer Deposition of ultrathin aluminum oxide on monolayer MoS2 exfoliated on gold: the role of the substrate” Adv. Mater. Interfaces, 8, 2101117 (2021).
[3] E. Schilirò, F. Giannazzo, S. Di Franco, G. Greco, P. Fiorenza, F. Roccaforte, P. Prystawko, P. Kruszewski, M. Leszczynski, I. Cora, B. Pécz, Z. Fogarassy, R. Lo Nigro, “Highly homogeneous current transport in ultra-thin aluminum nitride (AlN) epitaxial films on gallium nitride (GaN) deposited by plasma enhanced atomic layer deposition” Nanomaterials, 11(12), 3316 (2021).