Except they are used in the production the semiconductors that control EVs, battery charging, etc. What is thallium needed for in semiconductor manufacturing?

Except they are used in the production the semiconductors that control EVs, battery charging, etc. What is thallium needed for in semiconductor manufacturing? I tried searching Google Scholar and didn't turn up anything relevant. I've never seen thallium mentioned alongside semiconductor production in chemistry handbooks or chemical engineering encyclopedias either. Global thallium production declined from 15,000 kilograms in 1994 [1] to less than 8,000 kilograms in 2018 [2] even as semiconductor production volumes increased enormously, so I am skeptical that thallium is needed for semiconductor production. Mercury is banned in alkaline batteries in the US since 1996: https://www.epa.gov/mercury/mercury-batteries https://www.epa.gov/mercury/mercury-batteries Panasonic claims that the battery mercury ban is worldwide now (and they should know), but unfortunately does not cite the relevant legislation: https://www.panasonic-batteries.com/en/news/mercury-batteries-why-they-were-popular-and-banned https://www.panasonic-batteries.com/en/news/mercury-batterie... [1] USGS mineral commodity summaries, "thallium", 1996: https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/production/mineral-pubs/thallium/thallmcs96.pdf https://d9-wret.s3.us-west-2.amazonaws.com/assets/palladium/... [2] USGS mineral commodity summaries, "thallium", 2018: https://d9-wret.s3-us-west-2.amazonaws.com/assets/palladium/production/atoms/files/mcs-2019-thall.pdf https://d9-wret.s3-us-west-2.amazonaws.com/assets/palladium/...