The interfacial electronic states of a Pt/HfO2/Pt diode were investigated by using hard X-ray photoelectron spectroscopy under bias operation. The application of a forward bias to the Pt/HfO2/Pt diode increased the Pt–O bonding peak, providing evidence of Pt electrode oxidization and oxygen vacancy formation around the Pt/HfO2 interface. Under a reverse bias, hafnium was drawn to the Pt electrode, where it took part in Hf–Pt bonding. Direct observations were made of oxygen migration at a Pt/HfO2 interface under device operation, which was the key to controlling the electrical properties of metals on oxides.

Oxygen Migration at Pt/HfO2/Pt Interface Under Bias Operation. T.Nagata, M.Haemori, Y.Yamashita, H.Yoshikawa, Y.Iwashita, K.Kobayashi, T.Chikyow: Applied Physics Letters, 2010, 97[8], 082902