Application for a PhD in Germany: how specific do I need to be about my thesis plans?

Question

I've just finished my master's degree in physics and now I'm searching for a PhD position. I found a working group at a German university that is searching for some PhD students. In the vacancy it is asked for a CV and a statement of research interest. I know that I should write my motivation, qualification etc. for working at the research theme. But how precisely am I supposed to give the topic of my doctoral thesis? Is it sufficient to have a broader view of the topic and themes the working group is dealing with or is it necessary to formulate the concrete topic of my planned thesis? Also should the statement be part of the CV or should it be a separate document?

Answer 1

But how precisely am I supposed to give the topic of my doctoral thesis? Is it sufficient to have a broader view of the topic and themes the working group is dealing with or is it necessary to formulate the concrete topic of my planned thesis?

In general, most hiring PIs will want to see that you have "done your homework", that is, you have a good idea what the group does and that you're motivated to work on these kinds of things.

On a more specific level, you should address any concrete hints from the job advertisement. It's a good idea to be as specific as possible and mention a few ideas for topics you would like to work on. But unless the job advertisement explicitly asks you to do so, it wouldn't be required to have a detailed proposal of your thesis project.

Also should the statement be part of the CV or should it be a separate document?

If the advertisement explicitly asks for a "CV and statement of research interest", it should be two separate documents.