Thermionic emission driven resistive switching behaviour in Ca and Sr doped YMnO3 thin film devices

Abstract

In this communication, we report the resistive switching (RS) behavior of pulsed laser deposition (PLD) grown with 5% Ca and Sr doped YMnO3 [referred with general formula as Y0.95A0.05MnO3 (YAMO), where A = Ca or Sr; YCMO if A is Ca and YSMO if A = Sr] on (100) single crystalline Nb:SrTiO3 (SNTO) substrates. The thickness of both the YCMO and YSMO thin film devices were ∼300 nm. The hysteretic current–voltage (I–V) characteristics were measured at 100 and 300 K across the YAMO/SNTO interfaces using current perpendicular to plane (CPP) transport measurement geometry. Both these devices exhibit distinct RS behaviours and these are highly influenced by the temperature, ionic size of dopants (i.e. Ca and Sr) and structural disorder as well as lattice mismatch between the films and substrates. While the YCMO/SNTO device exhibits an effective RS behavior in the reverse bias mode, the YSMO/SNTO device in the forward bias mode. The current compliance effects were observed for both the thin film devices and in both the bias modes and their modifications with different parameters. These results are discussed in the light of oxygen vacancies, their distribution and mobility. Thermionic emission model has been employed to understand the charge conduction mechanism across the YAMO/SNTO junctions. The variations in the barrier height has been obtained by fitting the experimental data of I–V with different temperatures, resistance states, dopants and bias modes and discussed in detail. Retention behaviours in the context of switching cycles and time duration have been studied at 100 and 300 K for the verification of device stability, reliability and reproducibility.