Au/Pd/Te ohmic contacts on n-type InP

Au/Pd/Te contacts on n-type InP have been studied and a contact resistance of 1 X 10(-4) OMEGA-cm2 was achieved on a doping level of 4 x 10(15) CM-3 and 1 x 10(-6) OMEGA-cm2 on 4 x 10(18) cm-3. This contact system reacts with the InP in a solid phase interaction to form an interface region of only 44 nm in thickness. A separate study of the interaction of Te with InP by X-ray diffraction and electrical sheet resistance measurements revealed that In2Te3 grew epitaxially on the InP. We believe this compound facilitates the ohmic contact formation by forming a thin layer doped with the released phosphorus and thus forms the interface between the InP and remaining elemental Te. Other electrical measurements show that Pd acts as a barrier during annealing preventing interaction of the Te and Au resulting in an acceptable post processing resistivity of 18 muOMEGA-cm for the ohmic contact metallization.