Hafnium oxide (HfO2) is currently considered to be a good candidate to take part as a component in charge-trapping nonvolatile memories. In this work, the electric field and time dependences of the electron trapping/detrapping processes are studied through a constant capacitance voltage transient technique on metal-oxide-semiconductor capacitors with atomic layer deposited HfO2 as insulating layer. A tunneling-based model is proposed to reproduce the experimental results, obtaining fair agreement between experiments and simulations. From the fitting procedure, a band of defects is identified, located in the first 1.7 nm from the Si/HfO2 interface at an energy level E-t = 1.59 eV below the HfO2 conduction band edge with density N-t = 1.36 x 10(19) cm(-3). A simplified analytical version of the model is proposed in order to ease the fitting procedure for the low applied voltage case considered in this work. (C) 2016 Elsevier B.V. All rights reserved.