Research profile
The research profile represents your professional qualification which you will later use to apply for a professorship. As a rule, the research profile is a common topic from one, at most two, main research areas and not a loose list of projects. Your doctoral work represents the first research focus. In the postdoc phase, your second research focus emerges through your publication activities or, if applicable, through a habilitation. During the profiling process, position yourself as interdisciplinary as possible without the profile becoming too vague or broad. On the way to your academic profile be innovative. This does not have to be immediate; possibly your topic may not become innovative for 5-10 years.
If you are still looking for a second research focus, take a look at university locations of your personal choice or in Germany in general and get an idea of which professors hold a professorship in your field and especially for how long.