2, Missouri University of Science and Technology, Rolla, Missouri, United States
The promise of next-generation electronics, which combines features, such as mechanical flexibility, optical transparency, and relatively low-cost, has attracted much attention over the past several years. In the quest of seeking promising candidate component materials, amorphous metal oxides (AMOs) stand out owing to their unique properties. Despite the fruitful research work on AMOs, much attention has been paid to the electrical properties, which leads to a lack of thorough study of some other important properties, such as the thermal stability.
AMOs commonly are indium oxides doped with other metal ions (such as Zn, Sn, Ga). Though it is known that the introduction of secondary metal cations will decrease the degree of crystallinity and elevate the crystallization temperature, the correlation between the altered local structures and the subsequent material thermal stability remains unanswered. Hence, a comprehensive thermal stability study of three classic ternary MO systems is carefully designed and conducted using both in situ synchrotron X-ray technique and ab initio MD simulation.
A series of amorphous In-M-O thin films (M=Sn, Zn and Ga) were deposited by PLD and then annealed under the isochronal annealing condition. The amorphous to crystalline transition of each film was measured by employing in situ grazing incident wide-angle X-ray scattering (GIWAXS) technique. The time-evolved degree of crystallinity (χc), crystallization time (τc) and crystallization temperature (Tc) are determined from the diffraction patterns. Ab initio molecular dynamics (MD) simulations were also carried out to provide a theoretical insight into the fundamental structural differences induced by additional cations. The local structural distortions and medium-range reorganization around In and added cations are quantified by comparing the key parameters of MO polyhedral, which will help to interpret the observed crystallization kinetics.