Memristor for Radiation sensing

Abstract

The development of environmental radiation monitoring and therapy have been influenced by the advancements of the semiconductor industry. Semiconductor based detectors such as Silicon and Metal Oxide (MOS) are known for both their low cost as well as miniature sizes. Nevertheless, the problem with MOS transistor is that the radiation induces charges which get trapped in the gate oxide. In specific, due to irradiation, the turned-on transistor reduces the threshold voltage which prevents the transistor from switching off back again, hence greatly damaging the circuitry. However, low cost, scalable, and repeatable detectors which can both operate at low voltage as well as possess natural behavior in the presence of radiation are a necessity. In this case, Memristor is considered an option due to the wide array of favorable characteristics it retains. Its metal-insulator-metal structure which is similar to the MOS detector promotes the memristor to be investigated as a radiation sensor. Furthermore, the scalability, thickness scaling, behavior repeatability and low operating power of the memristor results in emphasizing the necessity of investigating it as an option to detect the ionizing radiation. Therefore, a genuine classification for the existing radiation detectors have been achieved as a result of a comprehensively conducted review. This new classification is based on the collecting mechanisms, in specific the output of the detector indicates the effect of irradiation. Furthermore, in this research, a solution for the MOS transistor issue is proposed by investigating the electrical characteristics of a micro-thick memristor as a possible radiation sensor. Novel protocols for electrical testing have been conducted in order to study the memristor key features, such as the switching mechanisms. In addition, the set process along with its time dependency model as well as the reset process, retention and endurance are investigated for the first time in the literature for a micro-thick memristor. Experimental results proved that the ROFF/RON is 107 which indicates a good noise margin. It also demonstrated that a high endurance of more than 50 cycles has been detected. Further, it is the first micro-thick memristor to have repeatable switching mechanism indicated by its capability to be set at 0.6V and reset at -0.2V. Finally, statistical analysis for the electrical behavior prior, during and after ionizing irradiation is executed.

Date of Award	Apr 2017
Original language	American English
Supervisor	Baker Mohammad (Supervisor)