Technologies Available for License

2014-032: Method and Apparatus for Fabricating Thin Film Components with Tailored Properties

Invention: 2014-032

Patent Status: U.S. Patent Number 9,916,958 was issued on March 13, 2018

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Summary

High quantum efficiency photocathodes have a variety of applications-from photodetectors to light sources. Having tailored band structure of thin films could allow for better control over their electronic and optical properties, resulting in higher efficiency and versatility in photocathodes or other components. Fabrication techniques would need to be developed that allow for precise control over these characteristics at the nanoscale. This invention described methods and systems for fabricating a film, such as, for example, a photocathode, having a tailored band structure and thin-film components that can be tailored for specific applications, such as, for example photocathode having a high quantum efficiency.

Description

This invention focused on providing methods and apparatus for forming films with tailored properties, like photocathodes, which have specific band structures suited for practical applications. These films were made by synthesizing alkali antimonide compounds and depositing thin films on substrates starting with a liquid alloy which is formed by mixing two alkali materials, followed by the addition of a solid antimony material. This mixture then forms a ternary crystal compound (e.g., alkali antimonide, such as K₂CsSb). Thin films of K₂CsSb photocathode films with various compositions can be prepared by hot wall evaporation (HWE) onto glass substrates under a high vacuum (e.g., 10⁻⁶ to 10⁻⁷ Torr) condition. The resulting quantum efficiencies of the thin film photocathode were measured in-situ and real time during the film growth to optimize the HWE parameters towards maximum conversion efficiencies for a given composition of the source material.

Journal Publication & Intellectual Property

• US 9,916,958 B1 (.pdf)
• US 11,094,495 B1 (.pdf)
• US 11,881,391 B1 (.pdf)
• Bi-alkali antimonide photocathode growth: An X-ray diffraction study (.pdf)
• Sputter growth of alkali antimonide photocathodes: An in operando materials analysis (.pdf)
• Direct observation of bi-alkali antimonide photocathodes growth via in operando x-ray diffraction studies (.pdf)