Social Media is a broad topic which includes Facebook, Twitter, YouTube, PinInterest, Wikipedia, text messaging, Instant messaging, Skype, Facetime, social networking, social software, community technologies, and the like. Deaf people are enthusiastic users of Social Media because there are no communication barriers. Facebook is popular with the Deaf community, and Jessica Cuculick did her dissertation on how the Deaf community's use of Facebook. Check out the list of references at the end of her dissertation to find some related articles on this topic. There is a chapter written by Cuculick and Kurz in the book It's a Small World: International Deaf Spaces and Encounters about social media and deaf people.
Other sample dissertations are: The Deaf and HH on Social Networking Sites: Identity, Community Building and Connections Between Communities, The Use of Community-based Technologies to Enhance the Educational Experience for DHH in Higher Education, and Literacies, Mobilities and Agencies of Deaf Youth in Turkey: Constraints and Opportunities in the 21st Century.
Check out the Sage Deaf Studies Encyclopedia to get background information on this topic.