Pulse and Compliance Current-Dependent Negative Differential Resistance in BaTiO₃/Nb:SrTiO₃ Heterojunctions

The negative differential resistance (NDR) is closely related to the pulse and compliance current (CC) but not ferroelectric polarization in BaTiO3/Nb:SrTiO3 heterojunctions. The NDR feature shows an opposite trend on the positive (+VP) and negative pulse (−VP) and the same trend on pulse amplitude and width while maintaining the same polarity. When the applied pulse was small or short, the NDR characteristics are almost not influenced. With increase of the +Vp (−Vp) amplitude or width, NDR enhances (reduces) while shifting to a smaller (bigger) negative bias voltage (−Vb), and the low resistance state (LRS) reduces (enhances) while the high resistance state (HRS) almost remains unchanged. Furthermore, as CC increases, the NDR enhances markedly and barely shifts, while the LRS and HRS almost remain unchanged. Interestingly, the NDR location and LRS exhibit the same dependence on the amplitude/width of ±Vp and CC. The above behaviors of NDR can be attributed to the variance of oxygen vacancy (Vo) concentration and depletion layer width. It is beneficial for the development of NDR devices.