The Republic of Ireland Under-21 international has joined United on loan from Rovers until the turn of the New Year.
But the young winger - excited by the prospect of playing regular football - hopes to stay at Bramall Lane longer.
He told the club's official website: "I didn't need much persuading to come here, it is a Premier League club in my eyes.
"It's for six months initially but I'm looking at it being longer. I need to be playing, getting match fitness and hopefully I can impress here."