Visa
You must apply for a visa in your home country before entering the Federal Republic of Germany.
A list of the types of visas and the documents that have to be submitted along with the visa application is provided below:
A Schengen visa is issued for a short stay of up to three months per six-month period. It cannot be extended beyond three months or converted to a different type of residence title. You have to leave the country before the visa expires.
A national visa is issued to a person planning to stay in Germany for longer than three months or to pursue gainful employment. The national visa is also usually issued for a maximum period of three months. After your arrival in Germany, this type of visa has to be converted to a residence title with a longer period of validity at the Office for Foreigners in the city or town where you live.
Not all foreign researchers require a visa. EU or EEA nationals are not subject to any entry restrictions. Nor are those from Australia, Canada, Israel, Japan, New Zealand, South Korea, Switzerland or the USA since they may acquire a residence permit after entry. This regulation also applies to scholars from Andorra, Honduras, Monaco and San Marino as long as they do not intend to engage in gainful employment. In addition, there is a group of countries whose citizens may enter the country for three months without a visa, but are not eligible for a work permit and must leave the country at the end of this period. The visit cannot be extended and re-entry into the country is possible only with a national visa (see immediately below). The Federal Foreign Office has compiled a list of the countries affected by this regulation; it can be consulted at the following Web site:
The reform of the Immigration Act created a new type of residence title especially for researchers: the 'research visa' or 'researchers' residence permit' (§ 20 AufenthG). This residence title entitles the holder to engage in teaching activities and other gainful employment related to the designated research project.
The new residence title was introduced to make it easier for researchers from non-EU countries to enter Germany and live here for periods longer than three months, to speed up visa procedures, and to give the researchers greater mobility inside the EU.
» more at: EURAXESS - Germany