research officer
Official title for a researcher in government, public institutions, or large organizations. Often used in formal contexts.
He was hired as a research officer at the national research institute.
A doctoral degree is required to apply for the research officer position.
He became a research officer at the national research institute.
As a research officer, she proposed a new policy.
研究者 is the broad, everyday word for anyone doing research, whereas 研究官 refers specifically to a person holding an official researcher post in a government or institutional hierarchy.
Compound of 研究 (research) and 官 (official, government position). The term likely originated in Meiji-era institutional naming conventions.