To find theses by Ohio State authors, you can use the Advanced Search in Libraries Search and limit your search to the Library Catalog and specify Resource Type: Theses (see mage below).
If you want a specific author or title, you can specify where search terms appear by changing Any Field dropdown.
Since Libraries Search finds theses and dissertations from many locations. In order to specify you want content from Ohio State, consider adding another search box and place in it:
"Ohio State University"
Include the quotes. For example:

Note: Finding theses and dissertations by department name may be difficult as departments' names have changed over time. The next box has info on how to see department lists for electronic theses and dissertations. Note there may be variations and changes in department names in this list.
Ohio State theses not found in the OhioLINK ETD Center can be scanned and delivered as a free PDF. Any individual may email libill@osu.edu directly to make a digitization request. Please include the following information: Author, Title, & Call Number (see above directions for searching the catalog). After scanning the material, we will email you a link to the PDF on our local server. PDFs will be stored on the server for 15 days.