Tunneling electroresistance of MgZnO-based tunnel junctions

Abstract

We investigated the tunneling electroresistance (TER) in metal/wurtzite-MgZnO/metal junctions for applications in nonvolatile random-access memories. A resistive switching was detected utilizing an electric-field cooling at ±1 V and exhibited a TER ratio of 360%–490% at 2 K. The extracted change in the average barrier height between the two resistance states gave an estimation of the MgZnO electric polarization at 2.5 μC/cm2 for the low-temperature limit. In addition, the temperature-dependent TER ratio and the shift of the localized states energies at the barrier interface supported the ferroelectric behavior of the MgZnO tunnel-barrier. From the first-principles calculations, we found a similar effect of the barrier height change coming from the reversal of ZnO electric polarization. The possibility of using metal electrodes and lower growth temperatures, in addition to the ferroelectric property, make the ZnO-based memory devices suitable for CMOS integration.

Great Enhancement Effect of 20–40 nm Ag NPs on Solar-Blind UV Response of the Mixed-Phase MgZnO Detector

“…The two types of breakdown devices have been widely used in high-performance infrared detectors, 48 , 49 and some similar structure UV detectors have also been reported. 50 , 51 The UV response of a detector is higher after break down through the high-resistance part by the photogenerated carriers in the devices, such as for graphene/PbS quantum dots (10 7 A/W), 52 graphene/CH 3 NH 3 PbBr 2 I (10 5 A/W), 53 and ZnO–Ga 2 O 3 (1.3 × 10 3 A/W at 255 nm UV light). 46 Both high-resistance c-MgZnO and low-resistance h-MgZnO exist in the MgZnO thin film.…”

Large nonvolatile control of interfacial magnetic anisotropy in CoPt by a ferroelectric ZnO-based tunneling barrier

“…The P reversal changes the chemical potential at interface, that should have a prominent effect on MAE due to the large 5d SOC [30]. Therefore, the system of CoPt (1 1 1)/Mg-ZnO (0 0 0 1) [31,32] has a strong potential for a large control of MAE.…”

“…Due to the large electric coercivity of MgZnO, the cooling under an electric field (EFC) from above the MgZnO Curie temperature was used to align P in either direction [Fig. 1(a)] [32]. The reversal of P results in a difference of the equilibrium surface charge at the surfaces of the FM electrodes [Fig.…”

“…The considerations behind the choices for the modeled structure and more details of the calculation methods are available in Ref. [32]. The density of states (DOS) was calculated for magnetization orientations at the inplane x and out-of-plane ẑ directions for each of P + and P − states, while the SOC was included [Figs.…”

“…There is a hybridized peak in d 3z MAE observations from resistance-field curves -We conducted experimental confirmations, using observations by resistance-field (R-H) curves with the field applied in the x and ẑ directions. The presented experimental results were obtained from samples described previously [31,32]. The initial film structure was made of (thicknesses in nm): c-plane sapphire Al 2 O 3 substrate/Pt (30)/Co 0.3 Pt 0.7 (10)/Mg 0.23 Zn 0.77 (7)/Co (16).…”