Switching behavior of indium selenide-based phase-change memory cell

A cross-point-type phase-change random access memory (PRAM) cell without an access transistor is successfully fabricated with the In₂Se₃ resistor, which has much higher electrical resistivity than conventionally used Ge₂Sb₂Te₅ and of which electrical resistivity can be varied by the factor of 10⁵ related with the degree of crystallization. Thus, the switching power can be delivered more effectively due to its higher electrical resistivity and device failure related to phase decomposition can be avoided since In₂Se₃ is single phase binary compound. The static-mode switching (dc test) is tested for the 5 μm In₂Se₃ PRAM device. In the first sweep, the as-grown amorphous In₂Se₃ resistor showed the high resistance state at low voltage region. However, when it reached the threshold voltage, the electrical resistance of the device was drastically reduced through the formation of an electrically conducting path. The pulsed-mode switching of the 5 μm In₂Se₃ PRAM device shows that the reset (crystalline → amorphous) of the device was done with a 70 ns 3.1 V pulse and the set (amorphous → crystalline) of the device was done with a 10 μs 1.2 V pulse. Reading was accomplished by measuring the device resistance at 0.2 V and as high as 100 of switching dynamic range (ratio of R_high to R_low) was observed.