Inorganic Low Cage-molecular Crystals.

For the interlayer dielectric in microelectronics, light element compounds are preferably accepted due to less electronic polarization. Here, the nontrivial dielectric nature of the SbO cage-molecular crystal, known as α-antimony trioxide (α-SbO), is reported. The gas-phase synthesized α-SbO nanoflakes are of high crystal quality, from which the abnormal local admittance responses were revealed by scanning microwave impedance microscopy (sMIM). The remarkably low dielectric constant (), 2.0∼2.5, is corroborated by the analysis of the thickness-dependent sMIM-capacitance signal. In light of the theoretical calculations, the ultralow molecular density and the significantly suppressed ionic polarization are both crucial to the highly reduced . Combining with the excellent optical band gap, thermal stability, and breakdown strength, α-SbO is a promising low dielectric.