Atomic layer processing and its applications

Abstract

Nanotechnology has revolutionized electronics, energy, and healthcare over the past few decades, significantly enhancing our daily lives. Atomic layer processing (ALP), which includes atomic layer deposition (ALD) and atomic layer etching (ALE), enables precise manipulation of material deposition and etching at the atomic level, further driving the advancement of nanotechnology and its associated applications. This dissertation focuses on the study some aspects of ALP, encompassing both ALD and ALE, and explores its applications. Firstly, an ALD-assisted method for synthesizing VO2 was developed through a combination of a non-stoichiometric vanadium oxide (VOx) ALD process and a tailor-made annealing process. The ALD-assisted VO2, characterized by its insulator-to-metal transition properties, was extended to two-dimensional and three-dimensional device applications to investigate its potential from both electrical and optical perspectives. Electrically, thin-film memristors and Si-Al2O3/VO2 core/shell memristors based on ALD-assisted VO2 demonstrated excellent switching performance and high sensitivity to temperature variations. Optically, three-dimensional inverse opal photonic crystals based on VO2 were prepared using ALD-assisted VO2 synthesis with polystyrene opal sacrificial templates. These photonic crystals displayed remarkable control over the photonic bandgap in the near-infrared (NIR) region, which can be reversibly switched by adjusting the external temperature. They also exhibited a temperature-dependent transition from a narrow-band NIR reflector to a broadband absorber. In addition, a novel thermoelectric-based position-sensitive detector (T-PSD) was proposed, along with a corresponding decoding strategy. This innovation has been proven effective for detecting single hot spots originating from various energy sources, including electromagnetic radiation, electrons, and macroscopic mechanical heat. Finally, a directional ALE process was developed for etching SiO2 using SF6 gas and Ar plasma near room temperature. This process achieved 100% synergy and a stable etching rate of approximately 1.4 Å per cycle. These studies have already demonstrated significant practical potential and may contribute to the further development of ALP-related nanotechnologies and applications. Additionally, the findings may provide deeper insights in turns into the underlying physics, materials science, and engineering principles involved.