Effects of biased irradiation on charge trapping in HfO2 dielectric thin films

Yifei Mu, Ce Zhou Zhao*, Qifeng Lu, Chun Zhao, Yanfei Qi, Sang Lam, Ivona Z. Mitrovic, Stephen Taylor, Paul R. Chalker

*Corresponding author for this work

Research output: Chapter in Book or Report/Conference proceedingConference Proceedingpeer-review

5 Citations (Scopus)


This paper reports the low-dose-rate radiation response of Al-HfO2/SiO2-Si MOS devices, in which the gate dielectric was formed by atomic layer deposition (ALD) with 5-nm equivalent oxide thickness. The degradation of the devices was characterized by a pulse capacitance-voltage (CV) and on-site radiation response technique under continuous gamma (γ) ray exposure at a relatively low dose rate of 0.116 rad (HfO2)/s. Compared with conventional CV measurements, the proposed measurements extract significant variations of flat-band voltage shift of the hafnium based MOS devices. The large flat-band voltage shift is mainly attributed to the radiation-induced oxide trapped charges, which are not readily compensated by bias-induced charges produced over the measurement timescales (for timescales less than 5 ms). A negative flat-band voltage shift up to -1.02 V was observed under a positive biased irradiation with the total dose up to 40 krad (HfO2) and with the electric field of 0.5 MV/cm. This is attributed to net positive charge generation in the HfO2 oxide layer. The generated charges are transported towards the HfO2/SiO2 interface, and then form effective trapped holes in the HfO2. Similarly, a positive flat-band voltage shift up to 1.1 V was observed from irradiation under negative bias with an electric field of -0.5 MV/cm. The positive shift is mainly due to the accumulation of trapped electrons. Analyses of the experimental results suggest that both hole and electron trapping can dominate the radiation response performance of the HfO2-based MOS devices depending upon the applied bias. It was also found there was no distinct border traps with irradiation in all cases.

Original languageEnglish
Title of host publication4th International Conference on the Advancement of Materials and Nanotechnology, ICAMN IV 2016
EditorsRoshidah Rusdi, Mohd Sufri Mastuli, Nurhanna Badar, Norlida Kamarulzaman
PublisherAmerican Institute of Physics Inc.
ISBN (Electronic)9780735415577
Publication statusPublished - 11 Sept 2017
Event4th International Conference on the Advancement of Materials and Nanotechnology, ICAMN 2016 - Langkawi, Malaysia
Duration: 9 Nov 201611 Nov 2016

Publication series

NameAIP Conference Proceedings
ISSN (Print)0094-243X
ISSN (Electronic)1551-7616


Conference4th International Conference on the Advancement of Materials and Nanotechnology, ICAMN 2016


  • Charge Trapping
  • HfO
  • Thin Films

Cite this