All researchers should spend some time in foreign research institutions but, unfortunately, the first thing I have to check whenever I get an email from a researcher X that wants to do a stay with my group is whether X expects me to pay him a salary.
If the answer is YES you better 1 – have a great CV, 2- propose a research topic that excites me and 3 – be lucky enough to contact me in one of the few occasions in which I may have funding available. And be aware, funding is usually linked to a specific project so we’ll need to sort that out as well
If the answer is NO then things get much easier. As long as you convince me that your presence could benefit the team in some way you’ll get the green light and you’ll be free the pursue your own research ideas (of course, within the scope of the things that interest us but I’ll not force you to take a topic in my own agenda).
So, before contacting somebody for a research stay do the homework and explore what are the options to get your own funding to cover the expenses of your stay. This is (or at least was) easier than you think, check the possibilities at all levels (national, regional, european,…). For instance, the Catalan government paid my 4 months in Italy and my almost two years in Canada. And for this second one, the acceptance rate was close to 50%!! (getting a paper accepted in a good conference is much more difficult than this!)
As much as we would like to receive lots guests researchers, research groups suffer always from funding problems so please contribute!