Abstract
Resistive random access memory (RRAM) characteristics using a new Cr/GdOx/TiN structure with different device sizes ranging from 0.4 × 0.4 to 8 × 8 μm2 have been reported in this study. Polycrystalline GdOx film with a thickness of 17 nm and a small via-hole size of 0.4 μm are observed by a transmission electron microscope (TEM) image. All elements and GdOx film are confirmed by energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy analyses. Repeatable resistive switching characteristics at a current compliance (CC) of 300 μA and low operating voltage of ±4 V are observed. The switching mechanism is based on the oxygen vacancy filament formation/rupture through GdOx grain boundaries under external bias. After measuring 50 RRAM devices randomly, the 8-μm devices exhibit superior resistive switching characteristics than those of the 0.4-μm devices owing to higher recombination rate of oxygen with remaining conducting filament in the GdOx film as well as larger interface area, even with a thinner GdOx film of 9 nm. The GdOx film thickness dependence RRAM characteristics have been discussed also. Memory device shows repeatable 100 switching cycles, good device-to-device uniformity with a switching yield of approximately 80%, long read endurance of >105 cycles, and good data retention of >3 × 104 s at a CC of 300 μA.
Highlights
Resistive random access memory (RRAM) is one of the most potential candidates for future nanoscale non-volatile memory application [1,2,3,4]
The energy-dispersive X-ray spectroscopy (EDS) spectra correlates with positions 1, 2, 3, 4, and 5, as shown in Figure 2c, which confirms the presence of Cr, Gd, Ti, O, and N elements in the respective layers
High-resolution TEM (HRTEM) images confirm that a GdOx material exists as polycrystalline and thickness of GdOx layer is 17 nm
Summary
Resistive random access memory (RRAM) is one of the most potential candidates for future nanoscale non-volatile memory application [1,2,3,4]. Resistive switching characteristics of other RRAMs using binary oxides show high current operation [6,13,18], and it is reported rare at low current operation [7,8,14]. Many electrodes such as TiN, Pt, Ir, IrO2, W, Cu, and so on have been used and known to have high-performance RRAMs; the chromium (Cr) in a Cr/Gd2O3/TiN structure has not been reported yet.
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