Phase-change activities on gallium-doped indium oxide

This study investigated the phase-change activities on a gallium-doped indium oxide (Ga:InO) device that can be supplied with a constant heat flow via symmetric contact to a pair of rodlike heating elements. A device set/reset current of 0.8/18 μA and resistance window of 2.6× 105 to 107 can be found on Ga:InO with a 6.2 μ m2 device area and a thickness of 40 nm. Analysis of a log-log plot revealed slopes of 1.07±0.01 and -1.12±0.03 that were found to correlate with the switching current and resistance change between the high-/low-value states of the Ga:InO device area, respectively. These observations lead to the estimated energy densities of 1.77±0.11 pJ/μ m3 and 7.26±0.44 pJ/μ m3 required to initiate the set and reset process in Ga:InO, respectively. Through differential scanning calorimetry analysis and acceleration tests of the Ga:InO film and the device, an activation energy of ∼1.275±0.005 eV was found, which corresponded to the high-/low-resistance state change. A data retention time of ten years was further estimated when the Ga:InO device is operated at 75 °C. According to the transmission electron microscopy analysis, these observations are correlated with an amorphous to cubic phase transition in In2 O3, which takes place at a crystallization temperature of 252 °C, and suggest that the phase-change activities originate from the Joule heating effect. © 2010 American Institute of Physics.