Electrical Switching Characteristics of Ge1Se1Te2 Chalcogenide Thin Film for Phase Change Memory

The changes of the electrical conductivity in chalcogenide amorphous semiconductors, Ge1Se1Te2, have been studied. A phase change random access memory (PRAM) device without an access transistor is successfully fabricated with the Ge1Se1Te2-phase-change resistor, which has much higher electrical resistivity than Ge2Sb2Te5 and its electric resistivity can be varied by the factor of 105 times, relating with the degree of crystallization. 100 nm thick Ge1Se1Te2 thin film was formed by vacuum deposition at 1.5×10-5 Torr. The static mode switching (DC test) is tested for the 100 µm-sized Ge1Se1Te2 PRAM device. In the first sweep, the amorphous Ge1Se1Te2 thin film showed a high resistance state at low voltage region. However, when it reached to the threshold voltage, Vth, the electrical resistance of device was drastically reduced through the formation of an electrically conducting path. The pulsed mode switching of the 20 µm-sized Ge1Se1Te2 PRAM device showed that the reset of device was done with a 80 ns-8.6 V pulse and the set of device was done with a 200 ns-4.3 V pulse. KCI Citation Count: 1