Private-equity firm Carlyle Group has bought a $147-million minority stake in Nigeria’s Diamond Bank PLC, in the hopes that a new mobile banking service will boost the lender’s profits and customer base, WallStreetJournal reports.

Diamond Bank has added more than 600,000 mobile banking customers since it started offering its Y’ello bank account via mobile phone operator MTN a few months ago, according to the report. The bank aims to double its existing customer base and have 5 million mobile banking users by the end of 2015, CEO Uzoma Dozie told WallStreetJournal.

This is the fourth investment Washington, D.C.-based Carlyle has made from a $698-million fund for sub-Saharan Africa, which it completed raising this year. Other investments are in metals trader Traxys SA; J&J Africa, a logistics company; and agricultural supply chain company ETG.

The world’s largest private-equity companies are searching Africa for acquisitions, lured by higher growth rates and new opportunities in infrastructure and providing services to emerging consumer markets.

New York-based multinational private equity firm KKR made its first African acquisition this year, buying into an Ethiopian rose farm. KKR specializes in leveraged buyouts.

In Nigeria, private-equity firms are considering bids for drinks company Chi, WallStreetJournal reports.

“We are very bullish on the continent,” said Genevieve Sangudi, Carlyle managing director, in an interview. “We are here to stay.”