I'm a doctoral student and I've published several academic papers. My institution maintains a digital institutional repository, but it doesn't look like I can put copies of my work in it. When I finish my dissertation, a copy of that would go in the IR. It seems strange that the institution doesn't seem to have practices in place to take in other published work of students. Are there other academic institutions that allow this? If so, it would be great to have links to their policies.
Most university institutional repositories will allow students to submit their work, as the aim of an institutional repository is, generally, to capture the scholarly, research and creative output of a university. This would include work being created by faculty, of course, but also staff and students.
What differs between universities is the emphasis they place on different creators. At a large research university, increasing citation counts of faculty members will be a key consideration that may make the acquisition of faculty works a higher priority than student works. Liberal arts colleges will, based on their institutional missions as teaching centres, will be able to focus on undergraduate research on a level that many research universities would be unable to do.
I have recently become the Digital Repository Coordinator at a research university, and one of the challenges I face is trying to balance acquiring faculty and staff work vs. student work. Many of the faculty I have talked to, however, are excited by the potential of using the institutional repository as a way to showcase their students' work.
As a doctoral student, especially, I would assume that you would be able to submit work to your university's institutional repository. Looking at your profile, I believe that your university's repository does allow students to submit work (See http://digilib.gmu.edu/dspace/handle/1920/2883, for example). If it's not clear how to do so, contact your university's repository coordinator to make it happen! They'd more than likely be thrilled a student (1) knows what an institutional repository is, and (2) is interested in depositing their work.
I guess it is not correct for an institution to host the students' works, but Theses, Dissertations, and Technical Reports, in its internal digital library (usually open to externals). The reason is simple, most papers are published under copyright terms. This way, one is not allowed to host this "copyrighted" content, without the publisher permission. I see many departments, research groups, and so on, making public available the list of publications, with a link to the original source.
I don't know how common it is, but certainly some institutions allow student papers. For example, Harvard's repository "provides open access to peer reviewed scholarly articles authored or co-authored by faculty, staff, and students of the Faculty of Arts and Sciences" (http://dash.harvard.edu/handle/1/2). I can't think of any good reason to exclude students, so I'm puzzled by why a university would do that.
Have you tried asking your supervisor to deposit the papers? Certainly in the old days there was usually some kind of review process for technical reports which might still be applicable to solely-authored-by-students papers, but I should think that if it is actually published in a journal and/or a member of faculty will vouch for it then the repository should accept it.