Alloying of ALD metals

• Main Author: Chew, Jia Ying
• Other Authors: Alfred Tok Iing Yoong
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Engineering::Materials
• Online Access: https://hdl.handle.net/10356/157238
• Institution: Nanyang Technological University

As high entropy alloys (HEAs) continue to gain interest in many applications of today’s world, methods to produce this material of superior properties such as arc melting and powder metallurgy involves harsh conditions that will damage and influence properties of the HEAs. In addition to this, traditional methods used are mostly used to produce HEAs in bulk form. This study aims to address the shortcomings of conventional methods and develop a two-step approach to produce HEA thin films which is believed to be less invasive and more sustainable as compared to conventional methods. This approach consists of deposition of five noble metals by ALD, followed by joule heating to alloy the metal atoms deposited. The experimental part of this study begins with single metal deposition of the noble metals on individual substrates which will lay the foundation for five-layer metal films to be fabricated thereafter. The deposition of the single noble metals was conducted with higher number of cycles, achieving thicker metal layers. Characterization techniques were used to determine the morphology, crystal structure and composition of the samples. The successful deposition of the individual metal samples led to the deposition of the five-layer films which is essentially the combination of the individual processes performed separately onto a single substrate. XRD and EDX data of the five-layer films proved successful deposition of all five noble metals. Thereafter, the films were joule heated in which new bonds were formed, as the shift in characterization peaks were observed in the XRD pattern. Surface morphology of the HEAs and five-layer films before joule heating were noticed to be vastly different as compared to the samples with single metal deposited. Successful fabrication of HEAs implies versality of this two-step approach to the fabrication of HEAs involving other materials as well as HEAs with better properties and surface coverage during applications. However, more research has to be done to investigate the properties of the HEAs fabricated.