The transport of defects in nitrogen implanted TiO₂

The electrical current as a function of time (I-t) is measured for nitrogen implanted TiO2. The I-t curve indicates that there is a stopping time for the transport of defects. Using the space charge limited current (SCLC) theory and the Einstein relation, the mobility and diffusivity of defects are obtained. However, the obtained diffusivity cannot interpret the transport stopping time well. Thus the transport of defects may be not realized by hopping over the potential barrier, but by tunneling through the barrier. The theoretical resident time or the tunneling time of defect in the potential well is firstly obtained by a simple model. Then the resident time is calculated using our theory. The calculated resident time is not only in good accordance with our experiment, but also in good accordance with the results in reference. This indicates that the tunneling plays an important role on the transport of defects in our sample.