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An international team of researchers has introduced an innovative method with potential applications in high-performance memory devices, specifically neuromorphic memory chips inspired by brain function.

Indium selenide key in developing computing technologies

Ferroelectric materials such as indium selenide possess inherent polarizing characteristics and alter their polarity when exposed to an electric field. This property makes them attractive for memory technologies due to their exceptional endurance and writing speed. However, their storage capacity is limited because current methods can only activate a limited number of ferroelectric phases, and capturing these phases poses experimental difficulties.

Study co-author and leader of the KAUST team Xin He said that current techniques only trigger ferroelectric phases which have been challenging to capture experimentally.

The research team achieved a breakthrough by introducing protons to indium selenide, resulting in multiple ferroelectric phases. In their experiments, they combined this ferroelectric material with a unique transistor featuring a multilayered structure consisting of indium selenide, aluminum oxide protecting sheet, platinum, and porous silica.

In their experiments, this assembly played a crucial role. The platinum layer acted as voltage electrodes, while the porous silica provided protons to the ferroelectric film. By adjusting voltage levels, the team could control the ferroelectric phases, with higher positive voltages increasing protonation and stronger negative voltages decreasing it. Protonation was most significant near the silica and decreased further away. Interestingly, when the voltage was removed, the proton-induced phases reverted to their original state.

New phenomenon attributed to proton diffusion

Co-author Fei Xue said that they observed the unusual phenomenon as a result of protons diffusing out of the material to the silica. The group’s achievement in developing a movie with a flawless connection to silicon resulted in a device boasting remarkable proton injection efficiency, all while functioning at levels below 0.4 volts.

Xue concluded that their main challenge involved the reduction of the operational voltage. However, it became apparent that the efficiency of proton injection across the interface played a pivotal role in determining operational voltages and could be adjusted accordingly.