The German Academic Exchange Service (DAAD - Deutscher Akadamischer Austauschdienst) offers funding possibilities for students and researchers currently affiliated with a US university.
US citizenship is not an eligibility requirement.
If you are a student or a faculty at UCR and you are interested in doing research in Germany, you can contact me via email (boerge.hemmerling (add @ucr.edu)) or phone (951-827-5264) or contact the San Francisco Information Center of the DAAD directly.