It depends on the publishing contract with your publisher, as sometimes copyright is transferred to the publisher. In most cases, you are free to include in their dissertation material that they have submitted for formal publication, but other times you will need to submit a permission request, and the publisher will indicate how to request permission, which is often through the Copyright Clearance Center.
If you don’t have copies of the contracts, Sherpa Romeo gives you a quick overview of which publishers allow you to self-archive your work into an institutional repository. Most publishers allow institutional repository deposits, but others require your work to have been published for 12 months before it can appear in an institutional repository. Almost all publishers require that you provide a citation and link to the article from those publishers’ sites.
If you find that the journals you published with don’t allow repository deposit or self-archiving, there’s likely a strong fair use case for you to consider, in which case getting permission wouldn’t be necessary. Starting on page 14 of this document is a good explanation of what to consider.
