Using single or hybrid electrode structures, we investigated recess Ohmic contacts to AlGaN/GaN heterostructures. It is found that, depending on the structure, the contact resistance can be an increasing or a decreasing function of the overlap metal length. Based on analysis using a transmission line model, we extract the direct contact resistances between the sidewall metal and the two-dimensional electron gas at the AlGaN/GaN heterointerface, which are dependent on the sidewall metal type.