French student looking for an apartment in Aachen from 10/01/2017 to 03/31/2018

I am a fourth year French student in the Mechanical design department at Polytech’Lille – a French graduate engineering school which belongs to Lille 1 University – Science and Technology (France). I have been selected by my school to apply for a semester of study within Erasmus + program at the University of RWTH Aachen in the field of Mechanical Engineering during the academic year 2017-18.
That's why I'm looking for an accomodation in the city of Aachen (from 10/01/2017 to the 03/31/2018).
I'm looking for a totally furnished apartment, with a minimum size of 20m^2.
My father is going in a city near Aachen this weekend, so he could visit the apartment (he would prefer to visit it in the evening of Saturday).