Effects of substrate temperature on the structural, optical and resistive switching properties of HfO2 films

• Changes of optical and electrical properties of HfO2 films were studied.
• HfO2 structure changed from amorphous to crystalline with increasing substrate temperature.
• Substrate temperature affects the morphology, optical transmission and refractive index.
• A high resistance ratio of 104 in a device based on HfO2 is achieved.

We systematically investigated the effects of substrate temperature on the structural and optical properties and resistive switching behaviors of HfO2 films. HfO2 films were prepared by using electron beam evaporation under different substrate temperatures. The results show that with the increasing substrate temperature, the amorphous HfO2 films were transformed to the crystalline state and the spherical surface grain size also increases. All the HfO2 films exhibited high transmittance in the near ultra-violet and visible light regions, and the absorption edge revealed an obvious blue-shift with an increase of substrate temperature. The Ti/HfO2/ITO/glass device exhibited excellent bipolar resistive switching behaviors with a high resistance ratio of 104.