2021/02/06 by Alex Henning, Johannes D. Bartl, Henning, Alex +17
Engineering · Physics and Astronomy · #FOS: Physical sciences #GaN-based semiconductor devices and materials #Materials Science (cond-mat.mtrl-sci) #Semiconductor Quantum Structures and Devices #Semiconductor materials and devices
paper · pdf · doi:10.48550/arxiv.2102.03642
openalex publication_date 2021/02/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Atomic layer deposition (ALD) is an essential tool in semiconductor device\nfabrication that allows the growth of ultrathin and conformal films to\nprecisely form heterostructures and tune interface properties. The\nself-limiting nature of the chemical reactions during ALD provides excellent\ncontrol over the layer thickness. However, in contrast to idealized growth\nmodels, it is experimentally challenging to create continuous monolayers by ALD\nbecause surface inhomogeneities and precursor steric interactions result in\nisland growth during film nucleation. Thus, the ability to create pin-hole free\nmonolayers by ALD would offer new opportunities for controlling interfacial\ncharge and mass transport in semiconductor devices, as well as for tailoring\nsurface chemistry. Here, we report full encapsulation of c-plane gallium\nnitride (GaN) with an ultimately thin (~3 AA) aluminum oxide (AlOx)\nmonolayer, which is enabled by the partial conversion of the GaN surface oxide\ninto AlOx using a combination of trimethylaluminum deposition and hydrogen\nplasma exposure. Introduction of monolayer AlOx significantly modifies the\nphysical and chemical properties of the surface, decreasing the work function\nand introducing new chemical reactivity to the GaN surface. This tunable\ninterfacial chemistry is highlighted by the reactivity of the modified surface\nwith phosphonic acids under standard conditions, which results in\nself-assembled monolayers with densities approaching the theoretical limit.\nMore broadly, the presented monolayer AlOx deposition scheme can be extended to\nother dielectrics and III-V-based semiconductors, with significant relevance\nfor applications in optoelectronics, chemical sensing, and\n(photo)electrocatalysis.\n