Lama Mahmoud1 Maguy Abi Jaoude1 Baker Mohammad1 Sabina Abdulhadi1 Hamda Al Shehhi1

1, Khalifa University of Science and Technology and the UAE Space Agency, Abu Dhabi, , United Arab Emirates

Voltage or current-controlled memory-resistive switching in metal-insulator-metal (MIM) structures has been extensively explored in circuit-research, over the past 50 years, and is expected to continuously grow to expedite the establishment of the “memristor” technology in replacement to the conventional RRAM [1-3]. While the research on memristive devices is heavily pursued for advanced computing, alternative uses are emerging in environmental sensing, where the actual computing reservoir is tailored to co-act as an environmental signal transducer [4]. Sensing ionizing radiations is a hot topic in radiation protection and dosimetry [5], and an example target application of memristive materials are high-Z metal-oxides owing to their attractive photo-electrical properties and popularity among thermoluminescent dosimeters. In this study, the microstructure of native HfO2 memristor is engineered with gadolinia (Gd2O3) doping so as to examine the co-functionality of the novel high-Z computing reservoir, as a low power gamma-ray detector, under preliminary ambient conditions. In this work, a 2 mm × 2 mm crossbar micro-thick Ag(TE)/Hf1-xGdxO2(~50 µm)/Cu(BE) (where 0 ≤ x ≤ 50 at.%) MIM stack is developed via a sol-gel drop-coating technique. The effect of Gd(III) doping composition on the memristive switching behavior (i.e. unipolar or bipolar), resistance ratio, retention time and endurance of the device is systematically examined by electrical characterization, and is supported by SEM /EDX analyses to establish a preliminary understanding of the governing switching mechanism. The I-V measurement results on the native HfO2 memristor demonstrated a bipolar switching behavior with a high endurance (above 60 cycles) and large ROFF/RON window (up to 106). A key finding in this portion of the work is that the Gd2O3 doping in the HfO2 reservoir alters the memristive switching behavior of the native oxide. Moreover, measurable changes in key electrical characteristics of the doped memristor stack in response to Cs-137 662 keV gamma-rays used as a model (source activity ~0.67 MBq), are demonstrated and discussed.
The proposed project is in line with United Arab Emirates Space Agency’s Space Science, Technology and Innovation (ST&I) Roadmap aimed at developing enabling technologies for Space exploration, which is intended to accomplish the objectives of the UAE Space strategy.