High temperature ferroelectric domain wall memory

Abstract

For automotive and space applications, the nonvolatile ferroelectric domain wall random access memory (DWRAM) is required to work at a wide temperature range of −40 °C to +150 °C. However, the wall current generally decays with the retention time at high temperatures with the uncertain mechanism. Here we observed the peaked domain wall (DW) currents to decay with time at 450 K in LiNbO3 single crystals, which was correlated with the charge injection into domain wall regions in the mobility of 6.4 × 10−9 cm2/V·s. The extrinsic charge injection suppresses the intrinsic diode-like DW current due to the local Li/O vacancy redistribution to compensate the domain boundary charge. But the injected charge can be removed at an opposite poling voltage and can be frozen upon cooling down to 300 K. The traces of frozen wall regions become conducting upon the wall erasure. Once the memory write and read times are far shorter than the charge injection time, the DWRAM shows good retention of written information with a large on/off current ratio of ~104 at 450 K, suitable to the applications in some extreme conditions.