New Capabilities of HfO2 and Stacked TiO2-HfO2 Mem-Impedances

International audienceResistive Random-Access Memories (ReRAMs, or memristors), are attracting industry attention as a new technology to replace Flash nonvolatile memories. Further, the impedance value can be tuned by the adjustment of both resistance and capacitance values giving the MEM-Impedance (MEM-Z). In a recent work on HfO2 MEM-Z [1], we demonstrated that the imaginary part of Resistive Random-Access Memories could be switched by external bias.Thus, such devices could be used in tunable electronic circuits , such as reconfigurable impedance matching network, reconfigurable amplifiers, programmable filters and oscillators. In order to make possible these applications, a good control of the impedance value and the possibility to change the impedance range of use by an external excitation will be necessary.In this work, we first present new capabilities of HfO2 MEM-Z structures elaborated by atomic layer deposition (ALD). For that, various external excitations were tested as the amplitude of the alternating voltage, the temperature (from 25°C to 125°C), the frequency of the signal. Results will be discussed as a function of these excitations and their combination on the value of resistance and capacitance and on the range of set – reset.In a complementary study, we developed thin ALD TiO2-HfO2 stacks to create MEM-Z structures. The peculiar migration of defects which control impedance transition in such structures allows obtaining new performances for electronic application