Preparation and characterization of indium chalcogenide thin films: A material for phase change memory

The versatile resistive switching behavior of metal chalcogenide thin films is highly desired for the fabrication of phase change memory (PCM) - electronic devices. The In2(Te1-xSex)3 thin films might be one of the prime candidates for the application of PCM devices. In this paper, the effects of Se-Te in the phase change characteristics of In-Se-Te material are investigated by X-ray diffraction, Field emission scanning electron microscopy, the I-V measurement and the optical transmittance. The resistance ratio between the amorphous and crystalline states of In2(Te0.98Se0.02)3, In2(Te0.94Se0.06)3 and In2(Te0.90Se0.1)3 thin films are about two orders of magnitude. The stoichiometric phase change from In2(Te1-xSex)3 to In2Se3 and In2Te3 phases in all the samples have been observed from the temperature dependent I-V characteristics. The electrical switching occurs at 80 °C, Further rise in temperature leads no change in the threshold voltage after switching. For the In2(Te0.98Se0.02)3, In2(Te0.94Se0.06)3 and In2(Te0.90Se0.1)3 films, the forward biased current/threshold voltages are found to be about 8 μA/4.2 V, 6 μA/3.00 V and 4 μA/2.8 V respectively. The In2(Te1-xSex)3 thin film showed the high resistance state at low voltage region. However, when it reaches the threshold voltage, the resistance drastically reduced through the formation of conducting path. From these studies, it can be concluded that the effective way to enhance the comprehensive performance of In-Se-Te system is by varying the concentrations of the Te and Se and it may find potential application in switching volatile PCM devices.