Effect of Aluminum Doping on Performance of HfO<i>ₓ</i>-Based Flexible Resistive Memory Devices

Abstract

The Al-doped HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>x</i></sub> -based resistive memory devices have been fabricated on indium tin oxide (ITO)-coated polyethylene terephthalate (PET) flexible substrate at room temperature. X-ray photoelectron spectroscopy is used to extract the different doping percentage of Al which allows optimizing the switching performance. It improves the cycle-to-cycle and cell-to-cell uniformity of switching parameters by tuning the oxygen vacancies in HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>x</i></sub> layers. The 7.5% Al-doped HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>x</i></sub> -based flexible resistive memory device shows excellent switching characteristics such as resistance ratio ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&gt; 10^{3}$ </tex-math></inline-formula> ) and retention ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 10^{4}$ </tex-math></inline-formula> s). There is no degradation of memory window under the mechanical strain with bending radius ranging from 25 to 5 mm. The temperature-dependent resistive switching characteristics have also been studied. There is sufficient memory window ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$&gt; 10^{2}$ </tex-math></inline-formula> ) till <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 10^{4}$ </tex-math></inline-formula> s at elevated temperature. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${I}$ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}$ </tex-math></inline-formula> curve fitting shows the ohmic (hopping) conduction in low resistance state (LRS) and the trap-controlled space charge limited conduction (SCLC) in high resistance state (HRS), supported by Arrhenius plot.