The phrase "deepen the issue" is correct and can be used in written English.
This phrasal verb can be used when you want to talk about something making a problem or situation more serious and complex. For example, "The new evidence has deepened the issue, making it far more difficult to resolve."
Moreover, we aimed to deepen the issues of interest as identified by a previous questionnaire study.
Rosario's departure only deepened the issues the Rutgers program faces.
We hope our multidisciplinary approach can deepen the discussion of this issue.
"With his commentary, Grant cut through the noise to drive and deepen the national conversation on the issues of his people," the judges said.
The Mittal Institute engages in interdisciplinary research to advance and deepen the understanding of critical issues in South Asia and the region's relationship to the world.
We hope to set a standard among Catholic universities nationwide -- to broaden and deepen the discussion on this critical issue, creating an environment in which genuine solutions to climate change become possible.
Departing from the recognition of a paucity of literature on the distinct vulnerabilities of girls in time of conflict, this study sought to deepen the knowledge base on this issue by qualitatively exploring the sexual vulnerabilities of adolescent girls surviving abduction and displacement in Northern Uganda.
Failing to address these issues will deepen the chasm between rural and urban areas, with ominous implications for national cohesion.
Cameron's meeting with the king three years ago was a visit intended "to broaden and deepen the UK-Saudi partnership on issues from social development to security to business relations".
Next, a number of individual interviews were conducted in each region with single key players to better understand the social care systems (with a focus on the distance between formal and emerging characteristics) and deepen the analysis of certain critical issues that arose within the focus groups.
Federal officials have been slow to issue contracts to deepen the port and until that happens, the Bayonne site will remain more brown than green.
