Fabrication of TiN/Ge Contact with Extremely Low Electron Barrier Height

Abstract

We succeeded in improving a TiN/Ge contact by optimizing the TiN deposition. From contact resistance measurements of TiN/n+-Ge, the specific contact resistivity was determined to be 7.9×10-6 Ω·cm2 for a surface impurity concentration of 3.9×1019 cm-3, suggesting that an interlayer between TiN and Ge is conductive. It was also found that a peripheral surface-state current dominated the reverse leakage current of the contact. The leakage current was significantly decreased by the surface passivation using GeO2. The passivated TiN/p-Ge contact showed a high hole barrier height of 0.57 eV, implying an extremely low electron barrier height of 0.09 eV.