Popular question this week
Yes, increasingly theses are openly available online, searching via Google Scholar is a good place to start.
Looking at Library catalogues, research repositories and thesis databases are all good places to find out about theses in your research area. The Library has developed a Thesis information guide to finding research theses and dissertations to help get you started.
You can also request theses from other Libraries using the Interloan service, generally there is no cost and you will often receive a pdf copy of the thesis which is yours to keep.