phranque - 10:25 am on Mar 12, 2013 (gmt 0)
gTLD = generic top-level domain, such as .com, .net, etc
ccTLD = country code TLD such as .de, .at, etc
google doesn't provide a way to target language, only a specific geography.
google also claims to ignore any language attributes in HTML documents.
as far as geotargetting Germany-only, it would be most optimal if your german content were on a subdomain that could be hosted in Germany.
do you have any inbound links from german-language content or sites hosted in Germany?