There are at least 3 artists with that pseudonym:

(1) Damon Baxter a.k.a. Deadly Avenger produced two straight up electro EPs in '95 and '96 under the name Sem.

(2) Semothy Jones, a British record producer.

(3) A dance act from Mental Madness Records.

(4) Electronic / Future Bass Producer from Netherlands.
He continued to release under the name Sem until 2020, and from around 2021 he has been active under the name who's sem. https://soundcloud.com/whosem Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.