Ohmic contact formation mechanism of Au/Pt/Pd ohmic contact to p-ZnTe

초록

The ohmic contact formation mechanism and the role of Pt layer of Au(500 angstrom) Pt(500 angstrom)/Pd(100 angstrom) ohmic contact to p-ZnTe were investigated. The specific contact resistance of Au/Pt/Pd contact depended strongly on the annealing temperature. As the annealing temperature increased, the specific contact resistance decreased and reached a minimum value of 6 × 10-6 Ωcm2 at 200°C. From the Hall measurement, the hole concentration increased with the annealing temperature and reached a maximum value of 2.3 × 1019 cm-3 at 300°C. The Schottky barrier height decreased with the increase of annealing temperature and reached a minimum value of 0.34 eV at 200°C and it was due to the interfacial reaction of Pd and ZnTe. Therefore, the decrease of contact resistance was due to the increase of doping concentration as well as the decrease of Schottky barrier height by the interfacial reaction of Pd ZnTe. The specific contact resistances of Au Pd, Au/Pt/Pd and Au/Mo/Pd as a function of annealing time was investigated to clarify the role of Pt layer.