Effect of Surface Nitridation on the Ge/HfO_2 Interface

摘要

Effect of Ge surface nitridation, prior to HfO_2 deposition, on Ge/HfO_2 interface has been studied using low temperature measurements. C-V characteristics at room temperature show significant dispersion in nitrided devices compared to non-nitrided devices as a function of frequency. Electron trapping is found to be dominant as temperature was reduced to 140K. Estimated activation energies in nitrided and nonnitrided devices indicate that surface nitridation is introducing new trap levels in bulk oxide. Constant voltage stress shows hole trapping being dominant in non-nitrided devices. In nitrided devices, effect of both hole and electron trapping is observed at higher stress level and higher charge injection.